The MAL blood group system consists of one high prevalence antigen, AnWj, first identified in 1972. AnWj is carried on Myelin and lymphocyte protein (Mal), an integral multi-pass membrane proteolipid of 153 amino acid residues organised into four membrane-associated segments and four adjacent hydrophilic domains. Mal is located in glycosphingolipid and cholesterol-enriched membrane microdomains (GEMs) where it shuttles between the trans-Golgi network, plasma membrane and endosomes. It appears to be required for apical sorting and cellular transport, including the influenza virus haemagglutinin in polarised cells. Mal is encoded by a single gene MAL, located on chromosome 2, and comprising four exons.
Anti-AnWj is potentially clinically significant, usually a result of transient suppression of antigen expression. However, a small number of individuals have persistent, autosomally-recessive inherited AnWj-negative phenotype resulting from a large exonic deletion of the MAL gene. AnWj expression is also known to be markedly reduced on In(Lu) cells.
","allele_notes":"","assignees":[]},{"id":5,"isbt_number":5,"name":"Lutheran","symbol":"LU","category":"Blood Group System","approved":true,"version":33,"createdAt":"2024-04-29T09:32:19.455Z","updatedAt":"2025-11-27T13:57:55.584Z","description":"The Lutheran blood group system consists of 28 antigens carried on a single pass type 1 membrane glycoprotein (aka CD239, basal cell adhesion molecule, B-CAM, Lutheran glycoprotein) with five disulfide-bonded, extracellular, immunoglobulin superfamily (IgSF) domains, which has adhesion properties and may mediate intracellular signalling. There are two glycoprotein isoforms, products of alternative splicing of BCAM; the longer isoform, consists of 628 amino acids (NM_005581.4 transcript 1), whilst the shorter isoform, consists of 588 amino acids (NM_001013257.2 transcript 2).
Reference allele: LU*02
LU*02 encodes LU2, LU4, LU5, LU6, LU7, LU8, LU12, LU13, LU16, LU17, LU18, LU20, LU21, LU22, LU23, LU24, LU25, LU26, LU27, LU28, LU29, LU30
","allele_notes":"","assignees":["Christoph Gassner"]},{"id":12,"isbt_number":12,"name":"Xg","symbol":"XG","category":"Blood Group System","approved":true,"version":3,"createdAt":"2024-04-29T09:32:23.187Z","updatedAt":"2025-09-24T11:11:31.185Z","description":"The XG blood group system consists of 2 antigens carried on 2 single-pass glycoproteins, encoded by the genes XG and CD99, located in pseudoautosomal region 1 (PAR1) of the sex chromosomes. The Xg glycoprotein is encoded by the X chromosome only, while the CD99 glycoprotein is encoded by both X and Y chromosomes. On Y, only exons 1-3 of XG exist. Both genes encode single pass glycoproteins of 180 and 185 amino acids, respectively.","allele_notes":"","assignees":["Celina Montemayor"]},{"id":40,"isbt_number":40,"name":"PEL","symbol":"PEL","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:38.599Z","updatedAt":"2025-09-24T11:10:58.221Z","description":"The PEL blood group system consists of one high-prevalence antigen, PEL, initially included in the 901 series (see PMID 8928488). It is carried on the ABCC4 protein (ATP-binding cassette sub-family C member 4), member of the superfamily of ATP-binding cassette transporters. ABCC4 is also known as the multidrug resistance-associated protein 4 (MRP4). ABC proteins transport various molecules across extra- and intra-cellular membranes. This multi-pass protein consists of 1325 amino acids, with predicted 12 transmembrane domains and 6 extracellular loops. The protein is encoded by ABCC4, 281,641 bases, chromosome 13q32.1(chr13:95,019,835-95,301,475) (GRCh38/hg38). The rare PEL– null phenotype is associated with a moderately impaired platelet aggregation.","allele_notes":"","assignees":["Thierry Peyrard"]},{"id":36,"isbt_number":36,"name":"Augustine","symbol":"AUG","category":"Blood Group System","approved":true,"version":5,"createdAt":"2024-04-29T09:32:36.483Z","updatedAt":"2025-09-24T11:13:04.028Z","description":"The Augustine (AUG) blood group system consists of four antigens carried on a multipass membrane glycoprotein equilibrative nucleoside transporter 1 (ENT1). It consists of 456 amino acids with an intracellular amino terminus and extracellular carboxyl terminus.","allele_notes":"","assignees":["Thierry Peyrard"]},{"id":14,"isbt_number":14,"name":"Dombrock","symbol":"DO","category":"Blood Group System","approved":true,"version":12,"createdAt":"2024-04-29T09:32:24.279Z","updatedAt":"2025-11-27T15:03:37.384Z","description":"The Dombrock blood group system consists of 10 antigens carried on a GPI-linked glycoprotein (DO, ART4, CD297) that consists of 314 amino acids. It has a leader sequence and a GPI motif, both of which are cleaved from the membrane bound protein. The DO gene consists of 3 exons distributed over 18 kb of gDNA.
Reference allele: DO*02
DO*02 encodes DO2, DO3, DO4, DO5, DO6, DO7, DO8, DO9, DO10
","allele_notes":"","assignees":["Lilian Castilho"]},{"id":37,"isbt_number":37,"name":"Kanno","symbol":"KANNO","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:36.978Z","updatedAt":"2025-09-24T11:10:57.416Z","description":"The KANNO blood group system consists of one antigen, KANNO1, carried on a GPI-linked glycoprotein (PrP, CD230) that consists of 253 amino acids. It has a leader sequence of 22 amino acids and a GPI motif of 23 amino acids, both of which are cleaved from the membrane bound protein.","allele_notes":"","assignees":["Yoshihiko Tani"]},{"id":23,"isbt_number":23,"name":"Indian","symbol":"IN","category":"Blood Group System","approved":true,"version":7,"createdAt":"2024-04-29T09:32:29.619Z","updatedAt":"2025-09-24T11:11:37.382Z","description":"The IN blood group system consists of 6 antigens carried on a glycoprotein (CD44) of 742 amino acids. The protein is found in many different tissues and multiple tissue-specific isoforms of CD44 exist. The haemopoietic form is approximately 81kDa.","allele_notes":"","assignees":["Yoshihiko Tani"]},{"id":38,"isbt_number":38,"name":"SID","symbol":"SID","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:37.523Z","updatedAt":"2025-09-24T11:11:42.005Z","description":"Sda or SID1, the only antigen of the SID blood group system, was discovered in 1967. About 90% of the European population carries the antigen on their red blood cells (RBCs). Although there are 10% missing the antigen on their RBCs only 4% lack expression in all tissues and fluids and thereby have the true null phenotype, Sd(a‒). The antibodies against Sda form a characteristic RBC agglutination pattern of small agglutinates surrounded by numerous free cells. The B4GALNT2-encoded transferase synthesizes the Sda antigen by the addition of an N-acetylgalactosamine to its precursors, which can be glycans on glycoproteins or glycosphingolipid conjugates (in the neolacto synthetic pathway). Alterations in B4GALNT2 that abolish transferase activity cause the Sd(a‒) phenotype. Another phenotype, the rare Cad or Sd(a++) or Super-SID, describes RBCs that are more strongly agglutinated by anti-Sda. If this trait is quantitative or qualitative is to date not fully understood, nor is its genetic background. Differences from reference allele SID*01 (accession number AJ517770) are given in the table.","allele_notes":"","assignees":["Asa Hellberg"]},{"id":33,"isbt_number":33,"name":"LAN","symbol":"LAN","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:34.867Z","updatedAt":"2025-09-24T11:10:16.935Z","description":"The LAN blood group system consists of one antigen, Lan, carried on a multipass membrane protein ATP binding cassette subfamily B member 6 (ABCB6) of 842 amino acids, encoded by the ABCB6 gene located on 2q35. ABCB6 is an ATP-dependent transporter of porphyrins (including heme) and is localized in the golgi apparatus, lysosomes, and plasma membranes. The biologically active protein is a homodimer. ABCB6 is up regulated during erythroid maturation. Mutations in ABCB6 underlie Lan null and variant phenotypes and are associated with familial pseudohyperkalemia and dyschromatosis universalis hereditaria.","allele_notes":"","assignees":["Vanja Crew"]},{"id":1,"isbt_number":1,"name":"ABO","symbol":"ABO","category":"Blood Group System","approved":true,"version":8,"createdAt":"2024-04-29T09:32:17.352Z","updatedAt":"2025-12-05T12:06:04.995Z","description":"The ABO system was discovered in 1900 and is considered the first and clinically most crucial system. The ABO gene and its 7 coding exons give rise to one of two principally different glycosyltransferases. The A glycosyltransferase (GTA) catalyzes the addition of a donor substrate, UDP-N-acetylgalactosamine, to an acceptor substrate known as the H antigen. The B glycosyltransferase (GTB) differs by only four amino-acid substitutions from GTA and performs the same enzymatic reaction but uses UDP-galactose as the donor substrate. In this way, genetic polymorphism gives rise to two related antigens in this system. Any polymorphism or mutation that changes the activity or specificity of the encoded enzyme may therefore alter the ABO phenotype. Alterations that completely abolish enzymic activity give rise to the blood group O phenotype, in which the H antigen remains unconverted, and no A or B antigen can be detected. If the genetic alteration decreases the enzyme's activity or alters its subcellular location, thereby decreasing the conversion of H to A or B, a weak A or B subgroup phenotype can result.
Furthermore, specific polymorphisms result in promiscuous enzymes synthesizing both A and B antigens, resulting in cisAB or B(A) phenotypes. The A phenotype is divided into A1 and A2. The former is more prevalent in all populations and has approximately five times more A epitopes per red cell. GTA1 is also better than GTA2 at synthesizing certain forms of A, e.g., A type 3 and 4.
In addition to the A and B antigens, two other antigens are included in the ABO system, namely A,B and A1. The former is a joint epitope on A or B antigen and is therefore present in both A, B and AB phenotypes. The exact biochemical nature of the A1 antigen has been more controversial but has been proposed to represent A type 4.
Reference allele ABO*A1.01 encodes A glycosyltransferase that synthesizes A antigen.
","allele_notes":"","assignees":["Martin L. Olsson"]},{"id":27,"isbt_number":27,"name":"I","symbol":"I","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:31.694Z","updatedAt":"2025-09-24T11:11:39.744Z","description":"The I blood group system consists of one antigen, I, carried on branched carbohydrate chains in the RBC membrane. The glucosaminyl (N-acetyl) transferase 2 that synthesizes I antigen on red cells consists of 402 amino acids and is encoded by the GCNT2 gene transcript containing exon 1C. The I– phenotype in adults is associated with cataracts.","allele_notes":"","assignees":["Nicole Thornton"]},{"id":34,"isbt_number":34,"name":"Vel","symbol":"VEL","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:35.403Z","updatedAt":"2025-09-24T11:11:41.293Z","description":"The Vel blood group system consists of one antigen that is dependent on the expression of SMIM1, a 78 amino acid single pass membrane protein, likely type 2. The protein is encoded by SMIM1. ","allele_notes":"","assignees":["Peter Ligthart"]},{"id":11,"isbt_number":11,"name":"Yt","symbol":"YT","category":"Blood Group System","approved":true,"version":7,"createdAt":"2024-04-29T09:32:22.647Z","updatedAt":"2025-09-24T11:13:26.062Z","description":"The Yt blood group system consists of 5 antigens carried on a membrane bound GPI-linked glycoprotein acetylcholinesterase (AChE) that consists of 617 amino acids. It has a leader sequence of 31 amino acids and a carboxyl-terminal GPI motif of 29 amino acids, both of which are cleaved from the mature erythrocyte isoform AChE-E. The protein is encoded by ACHE (or YT, acceptable if analysis is to predict a blood group antigen).","allele_notes":"","assignees":["Vered Yahalom"]},{"id":51,"isbt_number":46,"name":"ATP11C","symbol":"ATP11C","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-10-18T19:22:46.424Z","updatedAt":"2025-09-24T11:13:38.207Z","description":"The ATP11C blood group system currently consists of one high-prevalence antigen, LIL.\\n The LIL antigen is carried on the ATP11C protein, a flippase responsible for the active transport of phosphatidylserine (PS) from the outer to the inner leaflet of the membrane. ATP11C is described as the major flippase at the red cell membrane . However, the ATP11C protein is required for B cell maturation and differentiation as well. ATP11C is expressed ubiquitously in humans and mice. This multi-pass protein consists of 1132 amino acids (NM_173694.5 and NP_775965.3) with predicted 10 transmembrane helices and three cytosolic functional domains. The ATP11C protein forms a heterocomplex with its chaperone protein, CDC50A . The protein is encoded by the ATP11C gene, consisting in 218,931 pair bases, on chromosome Xq27.1 (chrX:139,726,346-139,945,276) (GRCh38/hg38). LIL– is a null phenotype caused by an ATP11C full gene deletion, resulting in the absence of the protein expression. This null phenotype was shown to be associated with mild anemia.\\nAn X-linked congenital hemolytic anemia was shown to be caused by a hemizygous missense mutation in the ATP11C gene (p.Thr418Asn), in a Japanese patient (Arashiki, N. et al. PMID: 26944472). Recently, a novel missense variant in the ATP11C gene (p.Leu789Phe), associated with mild hereditary hemolytic anemia, was described as well (Van Dijk, MJ, et al, PMID 37671681).\\nGenBank accessions in the ATP11C blood group allele table reference the genomic sequence NG_016550.3 (chrX:139,726,346-139,945,276) (GRCh38/hg38).","allele_notes":"","assignees":["Thierry Peyrard"]},{"id":47,"isbt_number":45,"name":"CD36","symbol":"CD36","category":"Blood Group System","approved":true,"version":7,"createdAt":"2024-05-14T16:24:07.226Z","updatedAt":"2026-02-04T06:47:13.879Z","description":"The CD36 blood group system consists of one antigen that is dependent on the expression of the CD36 protein, also known as platelet glycoprotein IV. CD36 is a 472 amino acid long multipass membrane protein with six cysteine residues linked by disulphide bonds. It is a multifunctional scavenger receptor with functions including fatty acid transport, lipid homeostasis, immune signalling and modulation. The CD36 gene comprises of 15 exons, with exons 1, 2, partial 3 and 15 being non-coding and partial 3-14 being the coding sequence. CD36 protein expression decreases during erythropoeisis and the mature red cells generally have low to no CD36 protein expression. Type I deficiency is characterized by the lack of CD36 protein on platelets, monocytes and red cell precursors. Type I CD36-deficient individuals are at risk of making antibodies.
We are aware that some CD36 alleles were omitted in this first iteration of the CD36 allele table because there was an ambiguity as to whether these alleles result in either type I or type II deficiency. We hope to include these alleles in a future iteration of the table when the classification/nomenclature system is improved sufficiently to accommodate such alleles. In the current table (Jan 2026), Null alleles only comprise alleles reported in individuals with type I deficiency.
Reference allele CD36*01 encodes: CD36.01.
","allele_notes":"","assignees":["Nuria Nogues"]},{"id":10,"isbt_number":10,"name":"Diego","symbol":"DI","category":"Blood Group System","approved":true,"version":24,"createdAt":"2024-04-29T09:32:22.103Z","updatedAt":"2025-09-24T11:13:44.747Z","description":"The Diego blood group system consists of 23 antigens carried on a multipass membrane glycoprotein called band 3 (aka AE1; SLC4A1; CD233). It consists of 911 amino acids and both amino and carboxyl termini are predicted to be intracellular. The transmembrane domains of band 3 function as the RBC anion transporter while the long amino terminal region of the protein is critical to maintaining RBC shape integrity through its interaction with the cytoskeleton.","allele_notes":"None","assignees":["Silvano Wendel"]},{"id":15,"isbt_number":15,"name":"Colton","symbol":"CO","category":"Blood Group System","approved":true,"version":6,"createdAt":"2024-04-29T09:32:24.823Z","updatedAt":"2025-12-05T11:58:05.458Z","description":"The Colton blood group system consists of four antigens carried on a multipass membrane glycoprotein called aquaporin 1 (AQP1; aka Channel-forming integral protein). It consists of 269 amino acids and both amino and carboxyl termini are predicted to be intracellular. The LRG_808 (NG_007475.2) includes more than one gene; the AQP1 gene encoding for the CO blood group antigens is located in the range 63301 to 77124.
Reference allele CO*01.01 encodes: CO1, CO3, CO4
","allele_notes":"","assignees":["Franz Wagner"]},{"id":22,"isbt_number":22,"name":"Knops","symbol":"KN","category":"Blood Group System","approved":true,"version":15,"createdAt":"2024-04-29T09:32:29.074Z","updatedAt":"2025-09-24T11:13:50.676Z","description":"The Knops blood group system consists of 9 antigens carried on a glycoprotein of 2039 amino acids and called the Complement Receptor I (CR1). It has a leader sequence of 41 to 46 amino acids, depending on translation initiation site, which is cleaved from the membrane protein. The coding sequence starts at nucleotide 28. The Helgeson phenotype, initially thought to be a KN serologic null, may be more likely the result of lower-level CR1 density and may also involve lack of a high-prevalence KN antigen [Pham Transfusion 2010 50(7):1435-43].","allele_notes":"","assignees":["Margaret Keller"]},{"id":45,"isbt_number":102,"name":"GATA1","symbol":"GATA1","category":"Transcription Factor","approved":true,"version":1,"createdAt":"2024-04-29T15:11:30.299Z","updatedAt":"2025-03-24T10:53:52.099Z","description":"This gene encodes a hematopoietic-specific transcription factor that induces high-level expression of adult beta-globin and other erythroid genes. The zinc-finger protein binds to the DNA sequence CCACACCCT found in the beta hemoglobin promoter. Heterozygous loss-of-function mutations in this gene result in the dominant In(Lu) blood phenotype. GATA1 does not represent a blood group system, but a mutation in this gene is responsible for an X-linked form of Lutheran-mod phenotype, XS2.","allele_notes":"","assignees":["Margaret Keller"]},{"id":20,"isbt_number":20,"name":"Gerbich","symbol":"GE","category":"Blood Group System","approved":true,"version":14,"createdAt":"2024-04-29T09:32:27.943Z","updatedAt":"2025-09-24T11:13:48.522Z","description":"The Gerbich blood group system consists of 13 antigens carried on a single pass type I membrane glycoprotein with called glycophorin C (GPC) and/or glycophorin D (GPD). GPC consists of 128 amino acids and GPD, the shorter isoform, has 107 amino acids. The glycoproteins are encoded by GYPC, or GE if analysis is to predict a blood group antigen.","allele_notes":"","assignees":["Peter Ligthart"]},{"id":3,"isbt_number":3,"name":"P1PK","symbol":"P1PK","category":"Blood Group System","approved":true,"version":5,"createdAt":"2024-04-29T09:32:18.455Z","updatedAt":"2025-12-05T12:00:27.073Z","description":"The gene A4GALT encodes 4-α-galactosyltransferase, the enzyme that synthesizes P1 and Pk antigens (1-3). The carbohydrate P1 antigen occurs on both glycolipids and glycoprotein whilst Pk is only known as a globoseries glycolipid. P1 glycolipid is synthesized with paragloboside as acceptor substrate and Pk antigen on lactosylceramide. Transcriptional regulation determines the two most frequent phenotypes in the P1PK blood group system, P1 and P2. A single nucleotide variant, rs5751348:G>T located in intron 1, found in homozygous form in P2 individuals, disrupts a binding motif for at least two transcription factors (EGR1, RUNX1) and results in decreased levels of enzyme-encoding A4GALT transcripts (2,4). P1 alleles encode both P1 and Pk antigens whilst P2 encodes only Pk. The rare NOR-encoding allele also encodes P1 and Pk (3). Null alleles encode a nonfunctional galactosyltransferase, resulting in the p (P1-Pk-NOR-) phenotype if inherited on both chromosomes.
Reference allele A4GALT*01 encodes P1 and Pk
","allele_notes":"","assignees":["Asa Hellberg"]},{"id":30,"isbt_number":30,"name":"Rh-associated glycoprotein","symbol":"RHAG","category":"Blood Group System","approved":true,"version":7,"createdAt":"2024-04-29T09:32:33.275Z","updatedAt":"2025-09-24T11:13:53.707Z","description":"The RHAG blood group system consists of three antigens carried on a multipass membrane glycoprotein called RhAG (Rh-associated glycoprotein; aka CD241). It consists of 409 amino acids and both amino and carboxyl termini are predicted to be intracellular. It is predicted to sit in the membrane in a tri-molecular complex with either RhD or RhCE in a 2:1 ratio. (1; PMID 16281947)","allele_notes":"","assignees":["Aline Floch"]},{"id":4,"isbt_number":4,"name":"Rh","symbol":"RH","category":"Blood Group System","approved":true,"version":58,"createdAt":"2024-04-29T09:32:18.959Z","updatedAt":"2025-12-05T12:19:39.649Z","description":"The Rh blood group system consists of 56 antigens carried on two proteins (RhD and RhCE) each consisting of 417 amino acids. Combinations (hybrids) between the two genes are not uncommon. The proteins consist of 12 membrane-spanning domains. The Rh blood group system consists of 56 antigens. Many are encoded at the RHCE locus and a number are encoded by hybrid RHCE with RHD. The RhCE protein (CD240CE) consists of 12 membrane-spanning domains and 417 amino acids. The amino and carboxyl termini are predicted to be intracellular, and the initial methionine is cleaved post-translationally. The expression of Rh proteins requires functional RhAG proteins, predicted to form heterotrimers with Rh.
RHCE:
Reference allele RHCE*01 encodes: RH4, RH5, RH6, RH17, RH18, RH19, RH26, RH29, RH31, RH34, RH44, RH46, RH47, RH51, RH57, RH58, RH59, RH61, RH62
Antigens commonly typed for include RH2 (C), RH3 (E), RH4 (c), RH5 (e), RH8 (Cw), RH9 (Cx), RH10 (V) and RH20 (VS).
The less common include RH11 (Ew), RH17 (Hr0), RH18 (Hr), RH19 (hrS), RH21 (CG), RH26 (clike), RH28 (hrH), RH31 (hrB), RH32, RH33, RH34 (HrB), RH35, RH36 (Bea), RH39, RH41, RH42, RH43 (Crawford), RH44 (Nou), RH45 (Riv), RH46 (Sec), RH47 (Dav), RH48 (JAL), RH49 (STEM), RH51 (MAR), RH53 (JAHK), RH55 (LOCR), RH56 (CENR), RH57 (CEST), RH58 (CELO), RH59 (CEAG), RH60 (PARG), RH61 (CEVF) and RH63 (CETW)
Compound antigens include RH6 (f), RH7 (Ce), RH22 (CE) and RH27 (cE).
RHD:
Reference allele RHD*01 encodes: information missing
Antigens encoded from either RHCE or RHD loci include RH12 (G), RH50 (FPTT), RH52 (BARC), RH54 (DAK), RH29 and CEWA (RH62)
","allele_notes":"","assignees":["Qing Chen","Aline Floch"]},{"id":29,"isbt_number":29,"name":"Gill","symbol":"GIL","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:32.735Z","updatedAt":"2025-09-24T11:10:55.175Z","description":"The GIL blood group system consists of one antigen carried on a multipass membrane glycoprotein aquaporin 3 (AQP3), an aquaglyceroporin. It consists of 292 amino acids and both amino and carboxyl termini are predicted to be intracellular.","allele_notes":"","assignees":["Peter Ligthart"]},{"id":62,"isbt_number":210,"name":"Collection (Le)","symbol":"210","category":"Collection","approved":true,"version":3,"createdAt":"2025-03-24T17:16:47.397Z","updatedAt":"2025-09-24T11:13:33.666Z","description":"The Collections (the 200 series) of blood group antigens represent red cell antigens which are biochemically, genetically or serologically similar but cannot be categorised into any system because the genetic basis has not yet been discovered.
The Cromer blood group system consists of 16 antigens carried on a GPI-linked glycoprotein (DAF, CD55) that consists of 381 amino acids. It has a leader sequence of 34 amino acids and a GPI motif of 28 amino acids, both of which are cleaved from the membrane bound protein.
Reference allele CROM*01 encodes: CROM1, CROM2, CROM5, CROM6, CROM7, CROM9, CROM10, CROM11, CROM12, CROM13, CROM14, CROM15, CROM16, CROM17, CROM18, CROM19, CROM20.
","allele_notes":"","assignees":["Christine Lomas Francis"]},{"id":8,"isbt_number":8,"name":"Duffy","symbol":"FY","category":"Blood Group System","approved":true,"version":7,"createdAt":"2024-04-29T09:32:21.023Z","updatedAt":"2025-12-05T12:32:32.002Z","description":"The Duffy blood group system consists of five antigens carried on a multipass membrane glycoprotein called the Atypical Chemokine Receptor 1 (ACKR1), CD234 (previously known as Duffy Antigen Receptor for Chemokines: DARC). It consists of 336 (major) and 338 (minor) amino acids. The major transcript is derived from exon 1 and exon 2 of ACKR1; the minor product is a transcript initiated at the beginning of exon 2. The amino terminus is predicted to be extracellular and the carboxyl terminus intracellular.
Reference allele FY*01 encodes: FY1, FY3, FY5, FY6
","allele_notes":"","assignees":["Nuria Nogues"]},{"id":2,"isbt_number":2,"name":"MNS","symbol":"MNS","category":"Blood Group System","approved":true,"version":58,"createdAt":"2024-04-29T09:32:17.915Z","updatedAt":"2026-02-04T15:51:56.552Z","description":"The MNS blood group system consists of 50 antigens carried on glycophorin A (GPA), glycophorin B (GPB) or on hybrids of these glycophorins. These proteins are single pass type I membrane glycoproteins that are heavily O-glycosylated. GPA carries an N-glycan. GPA consists of 150 amino acids, GPB of 72 amino acids and both have a leader sequence of 19 amino acids that is cleaved from the membrane bound protein. The hybrid proteins vary in length based on their composition but also have a 19 amino acid leader sequence. GPA is encoded by GYPA, GPB by GYPB. A third gene in this family, GYPE, normally does not encode detectable protein at the red cell surface but the gene has been shown to be involved in some gene rearrangements that encode cell-surface borne hybrid proteins. As described above, the proteins are encoded by GYPA or GYPB, or MNS if analysis is to predict a blood group antigen.
GYPA alleles
Reference allele: GYPA*02 (acceptable: GYPA*N or N if inferred by hemagglutination) (before October 2025: GYPA*01/GYPA*M)
Reference allele GYPA*02 encodes N, Ena, ENKT, ENEP, ENEH, ENAV, ENDA, ENEV antigens
Note: In most cases, the nucleotide changes also can occur on an N allele; these nucleotide changes are not given.
GYPB alleles
Reference allele: GYPB*04 (acceptable: GYPB*s or s if inferred by hemagglutination)
Reference allele GYPB*04 encodes N, s, JENU, and U antigens
Note: Expression of the U antigen involves GPB and another protein, probably RhAG. The amino-terminal of GPB, 20LSTTE24, is responsible for ‘N’ (MNS30).
MNS Hybrid alleles: MNS alleles created by gene rearrangement events within the GYP gene family.
Parent allele is GYPA for GYP(A-B), GYP(A-B-A), GYP(A-E-A) hybrid series
Parent allele is GYPB for GYP(B-A), GYP(B-A-B), GYP(B-E-B) hybrid series
MNS alleles with genetic variants encoding a null phenotype
GYP Deletion hybrids (GYP*01N, GYPA*28N.01)
GYPA Null alleles (GYPA*01N.02, GYPA*01N.03, GYPA*02N.01)
GYPB Null alleles (GYPB*05N.01 - GYPB*05N.04)
Please note that exon numbers for GYPB variants may differ by one position for exons downstream of the former pseudoexon 3, compared to earlier versions of the allele tables (PDF). The current allele tables do not count pseudoexon 3 since the reference transcript NM_002100.6 does not contain this pseudoexon.
Commentary regarding naming of unexpressed GYPA and GYPB alleles. Causal polymorphism for GPA (MNS28, Ena) negativity and GPB (MNS5, U) negativity is heterogenous. In both cases either gene mutations, or alternatively (almost) full gene deletions may be observed. We therefore chose to use GYPA*01N, or 02N to name unexpressed GYPA alleles with genomic sequences present. For (almost) full GYPA gene deletions we choose GYPA*28N. With respect to GPB, GYPB*03N and GYPB*04N alleles are considered to present (unexpressed) alleles, whereas GYPB*05N alleles represent (almost) full gene deletions.
","allele_notes":"","assignees":["Genghis Lopez"]},{"id":46,"isbt_number":101,"name":"KLF1","symbol":"KLF1","category":"Transcription Factor","approved":true,"version":1,"createdAt":"2024-04-29T15:11:30.911Z","updatedAt":"2025-03-24T10:53:20.948Z","description":"KLF1 encodes EKLF (erythroid Krüppel-like factor 1) which does not represent a blood group system. Variation in this gene is associated with In(Lu), a phenotype inherited in a dominant fashion. The In(Lu) phenotype is characterized by reduced expression of antigens of the Lutheran system and for P1, Inb, and AnWj antigens.","allele_notes":"","assignees":["Margaret Keller"]},{"id":43,"isbt_number":43,"name":"ABCC1","symbol":"ABCC1","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:40.126Z","updatedAt":"2025-09-24T11:12:33.789Z","description":"ABCC1 is also known as MRP1 “Multidrug Resistance Protein 1”. It was initially discovered in 1992 in a lung cancer cell line with a multidrug resistance phenotype(1). Cells with an increased expression show a resistance to drugs and xenobiotics. ABCC1 allows for the transport of various substrates involved in oxidative stress homeostasis, inflammation and nucleotide metabolism (efflux pump). In RBCs, ABCC1 has been described as an exporter of glutathione-S-conjugates and ATP.","allele_notes":"","assignees":["Thierry Peyrard"]},{"id":13,"isbt_number":13,"name":"Scianna","symbol":"SC","category":"Blood Group System","approved":true,"version":12,"createdAt":"2024-04-29T09:32:23.731Z","updatedAt":"2025-09-24T11:12:54.827Z","description":"The Scianna blood group system consists of 9 antigens carried on a single pass type I membrane glycoprotein (ERMAP) with 1 IgSF domain and an intracellular B30.2 domain. The 475 amino acid ERMAP protein is encoded by exons 3 to 12 from either a 3,485 bp (NM_001017922.1) or a 3,381 bp (NM_018538.3) mRNA transcript. There is a leader sequence of 29 amino acids, which is cleaved from the membrane bound protein.","allele_notes":"","assignees":["Bill Flegel"]},{"id":26,"isbt_number":26,"name":"John Milton Hagen","symbol":"JMH","category":"Blood Group System","approved":true,"version":9,"createdAt":"2024-04-29T09:32:31.195Z","updatedAt":"2025-09-24T11:13:51.471Z","description":"The JMH blood group system consists of eight antigens carried on a GPI-linked glycoprotein (CD108, Semaphorin, SEMA7A) that consists of 656 amino acids. It has a leader sequence of 44 amino acids and a GPI motif of 19 amino acids, both of which are cleaved from the membrane bound protein.","allele_notes":"","assignees":["Christoph Gassner"]},{"id":44,"isbt_number":44,"name":"Er","symbol":"ER","category":"Blood Group System","approved":true,"version":6,"createdAt":"2024-04-29T15:11:29.051Z","updatedAt":"2025-09-24T11:13:54.381Z","description":"The Er blood group system consists of five antigens carried on Piezo Type Mechanosensitive Ion Channel Component 1 (Piezo1). The protein comprises 2521 amino acid residues, 36 transmembrane domains, and one large extracellular domain (amino acids 2198 to 2431). Piezo1 is an important non-selective cation channel in a variety of tissues. The protein is encoded by a highly polymorphic single gene PIEZO1, associated with pathogenic mutations (e.g. dehydrated hereditary stomatocytosis, generalized lymphatic dysplasia, hemolytic anemia).","allele_notes":"","assignees":["Vanja Crew"]},{"id":57,"isbt_number":901,"name":"High Prevalence Antigens","symbol":"901","category":"Series","approved":true,"version":4,"createdAt":"2025-03-19T15:27:28.043Z","updatedAt":"2026-02-16T10:15:57.116Z","description":"The 901 series of blood group antigens represent a collection of high-prevalence red cell antigens (incidence of >90%) which cannot be categorised into any system or collection.
","allele_notes":"","assignees":[]},{"id":35,"isbt_number":35,"name":"CD59","symbol":"CD59","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:35.947Z","updatedAt":"2025-09-24T11:10:29.060Z","description":"The CD59 blood group system consists of 1 antigen carried on a 20 kDa glycosylphosphatidylinositol (GPI) linked glycoprotein (CD59). It consists of 128 amino acids and has a signal sequence of 25 amino acids. Another 26 amino acids are removed from the C-terminal end of mature protein which consists of 77 amino acids.","allele_notes":"","assignees":["Christoph Weinstock"]},{"id":61,"isbt_number":207,"name":"Collection (Ii)","symbol":"207","category":"Collection","approved":true,"version":2,"createdAt":"2025-03-24T17:10:07.758Z","updatedAt":"2025-09-24T11:09:11.904Z","description":"The Collections (the 200 series) of blood group antigens represent red cell antigens which are biochemically, genetically or serologically similar but cannot be categorised into any system because the genetic basis has not yet been discovered.
The H blood group system consists of one antigen, H, that is carried on glycolipids and glycoproteins on the RBC membrane, where it is synthesised by the fucosyltransferase product of the FUT1 gene; as well as on glycoproteins on epithelial cells and in body fluids, where it is synthesised by the fucosyltransferase product of the FUT2 gene. In group O individuals, H antigen is the terminal antigen however, in group A and B individuals, the H antigen serves as the precursor structure for A and B blood-group-specific glycosyltransferases.
Thus, group O people will test strongly H+ whereas groups A, B and AB will express very little H antigen. Mutations that negatively affect the α2FucT1 enzyme activity (encoded by FUT1) will result in reduced or absent H production (and a concomitant decrease in A and/or B antigens in individuals where those enzymes are encoded). Total absence of H, A and B antigens is called the Oh or Bombay phenotype. Weak expression is referred to as the paraBombay phenotype.
The enzymes α2FucT1and α2FucT2 are single pass type II membrane glycoproteins in the Golgi. The α2FucT1 protein consists of 365 amino acids and is encoded by FUT1 or H, if analysis is to predict a blood group antigen. The FUT2 gene produces two transcripts; one of 343 amino acids and another more abundant form of 332 amino acids. The longer transcript encodes a protein with approximately one fourth the enzymatic activity and the shorter form is considered to be the active enzyme. However, in accordance with the LRG project it has been decided in 2017, we still keep to use the nucleotide for the longer transcript translation to count the position for each variant. The α2FucT2 protein is encoded by FUT2 or Se, if analysis is to predict a blood group antigen.
","allele_notes":"","assignees":["Yanli Ji"]},{"id":60,"isbt_number":213,"name":"Collection (MN CHO)","symbol":"213","category":"Collection","approved":true,"version":7,"createdAt":"2025-03-24T12:48:19.259Z","updatedAt":"2025-09-24T11:09:16.199Z","description":"The Collections (the 200 series) of blood group antigens represent red cell antigens which are biochemically, genetically or serologically similar but cannot be categorised into any system because the genetic basis has not yet been discovered.
","allele_notes":"","assignees":[]},{"id":31,"isbt_number":31,"name":"FORS","symbol":"FORS","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:33.775Z","updatedAt":"2025-09-24T11:09:38.385Z","description":"The FORS blood group system consists of one antigen, FORS1 (rare), and this carbohydrate structure is present in the RBC membrane as part of the globo-series biosynthetic pathway of glycolipids. The terminal carbohydrate moiety is a GalNAc extension of the P antigen (globoside, Gb4). The glycosyltransferase that synthesizes the FORS1 antigen consists of 347 amino acids and is considered non-functional in most individuals. In antigen-positive individuals the glycosyltransferase is made active by an amino acid substitution due to a point mutation in exon 7. ","allele_notes":"","assignees":["Martin Olsson"]},{"id":25,"isbt_number":25,"name":"Raph","symbol":"RAPH","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:30.703Z","updatedAt":"2025-09-24T11:10:11.236Z","description":"The Raph blood group system consists of one antigen (MER2) carried on a multipass membrane glycoprotein CD151 of the tetraspanin family. It consists of 253 amino acids and both amino and carboxyl termini are predicted to be intracellular. The glycoprotein is encoded by CD151 (or RAPH, if analysis is to predict a blood group antigen).\\nThe null phenotype is associated with renal failure.","allele_notes":"","assignees":["Vered Yahalom"]},{"id":6,"isbt_number":6,"name":"Kell","symbol":"KEL","category":"Blood Group System","approved":true,"version":41,"createdAt":"2024-04-29T09:32:19.991Z","updatedAt":"2025-12-05T12:22:36.610Z","description":"The Kell blood group system consists of 38 antigens carried on a type II transmembrane glycoprotein of 732 amino acids (aka CD238). The Kell glycoprotein is a zinc-dependent metalloproteinase that has been shown to have endothelin-3-converting enzyme activity. A single disulfide bond (Kell Cys72 - XK Cys347) links the KEL protein to the XK membrane protein that carries the Kx antigen. The absence of XK reduces the expression of Kell antigens on the red blood cell membrane.
Reference allele KEL*02 encodes KEL2, KEL4, KEL5, KEL7, KEL11, KEL12, KEL13, KEL14, KEL16, KEL18, KEL19, KEL20, KEL22, KEL26, KEL27, KEL29, KEL30, KEL32, KEL33, KEL34, KEL35, KEL36, KEL37, KEL38, KEL40
Antigen alleles: KEL*01.xx and KEL*02.xx (altered antigens)
Null alleles: KEL*01N.xx and KEL*02N.xx (no expression of Kel antigens)
Mod alleles: KEL*01M.xx and KEL*02M.xx (very low expression of Kel antigens and immunisation risk)
","allele_notes":"","assignees":["Barbera Veldhuisen"]},{"id":7,"isbt_number":7,"name":"Lewis","symbol":"LE","category":"Blood Group System","approved":true,"version":10,"createdAt":"2024-04-29T09:32:20.483Z","updatedAt":"2025-12-05T12:30:39.128Z","description":"The Lewis blood group antigens, e.g. Lea and Leb, are part of carbohydrate moieties attached to lipids (fucosylated glycosphingolipids) and glycoproteins. These antigens are not intrinsic to red blood cells. Instead, they are enzymatically added to precursor molecules inside exocrine epithelial cells and, following synthesis, are excreted into various bodily fluids such as plasma from which the Lewis glycolipids are adsorbed onto the red cell membrane giving rise to the Lewis phenotypes. The glycoprotein forms mainly remain in plasma and other fluids. Lewis structures also appear on other cell surfaces and have functions in embryogenesis, tissue differentiation, tumour metastasis, inflammation, and bacterial as well as viral adhesion.
The biosynthesis of the Lewis antigens is dependent on the FUT3 gene that encodes an α(1,3/4)-fucosyltransferase protein (UniProt ID P21217) which catalyses the addition of fucose to a precursor polysaccharide. The biochemistry underpinning Lewis antigen synthesis is complex and cannot be detailed fully here – for more detail, please see Kukowska-Latallo et al., 1990 (PMID: 1977660) and Henry, 1996 (PMID:15387741). The type of Lewis antigen produced in this reaction depends on the type of precursor molecule the enzyme (Fuc-TIII) interacts with.
In individuals with an active FUT2 (Secretor or SE) gene, which encodes a fully active α(1,2)-fucosyltransferase (see H Blood Group System), predominantly Leb (and related Lewis antigens depending on ABO group, e.g. ALeb in group A) is made alongside trace amounts of Lea. The trace amounts of Lea produced are typically undetectable using serological methods, and usually, a Le(a–b+) phenotype is reported.
In individuals without an active FUT2 (Secretor or SE) gene, only Lea can be made as these “non-secretor” individuals cannot produce the precursor H type 1 antigen - this results in a Le(a+b–) phenotype.
In individuals with a partially functional FUT2 (Secretor) gene, the biosynthesis of the H type 1 precursor is hampered, and much more Lea can be made, resulting in a Le(a+b+) phenotype in “secretor-weak” individuals. This is because the enzymes produced by the FUT2 (Secretor) and FUT3 (Lewis) genes compete for access to the same unfucosylated precursor molecules, and the Lea antigen, once formed, cannot be converted into Leb. Although FUT2 (Secretor) generally outcompetes FUT3 (Lewis), some Lea is made, and hence Leb positive individuals always have trace amounts of Lea.
In individuals without a functional FUT3 gene, their RBC phenotype will have the Le(a–b–) regardless of the FUT2 status.
Reference allele FUT3*01.01 encodes an ACTIVE FUT3 gene.
IMPORTANT: Given the above information, the phenotype column in this table will report on the ACTIVITY status of the FUT3 enzyme, therefore, the ability to synthesize Lewis antigens. Inference of Lewis antigen phenotypes using the variants contained in this table should be done with regard also to the individual’s Secretor/H antigen status (i.e. the functionality of their FUT2 gene) as they are dependent on one another's functionality.
IMPORTANT: The FUT3 gene is reverse transcribed and the Lewis blood group reference transcript NM_000149.4 differs from the GRCh38/hg38 reference genome at two positions:
chr19:5844638 (genome: G, transcript: A) --> this corresponds to c.202T
chr19:5844526 (genome: A, transcript: G) --> this corresponds to c.314C
All allele definitions follow the transcript sequence as reference. This means that:
1. Alleles that match GRCh38/hg38 at either or both of these positions (i.e. those with variants c.202T>C and/or c.314C>T) will have no genomic change (shown as G>G and/or A>A in the hg38 Change column), reflecting the return to the genomic reference sequence at these positions.
2. Conversely, all alleles without the c.202T>C and/or c.314C>T variants match the transcript at these positions and therefore have GRCh38/hg38 changes (G>A at chr19:5844638 and A>G at chr19:5844526, respectively) that are not listed in the alleles variants but are implied.
","allele_notes":"","assignees":["Nick Gleadall"]},{"id":58,"isbt_number":700,"name":"Low Prevalence Antigens","symbol":"700","category":"Series","approved":true,"version":18,"createdAt":"2025-03-19T15:37:32.622Z","updatedAt":"2026-02-16T10:15:19.723Z","description":"The 700 series of blood group antigens represent low-prevalence red cell antigens (incidence of <1%) which cannot be categorised into any system or collection.
","allele_notes":"","assignees":[]},{"id":28,"isbt_number":28,"name":"Globoside","symbol":"GLOB","category":"Blood Group System","approved":true,"version":5,"createdAt":"2024-04-29T09:32:32.195Z","updatedAt":"2026-03-12T16:05:38.964Z","description":"The GLOB system was established in 2002 when the P antigen (globoside) was moved from the 209 collection. P is the most common neutral glycosphingolipid in the red cell membrane, belongs to the globoseries and has the following structure: GalNAcb3Gala4Galb4Glcb1 ceramide, also known as globoside (Gb4Cer). The B3GALT3 gene was first reported in 1998 by Amado et al. (1) to be a member of the b1,3-galactosyltransferase gene family and its product given the name b3Gal-T3. It was later shown by Okajima et al. (2) to possess UDP-N-acetyl galactosamine:globotriaosylceramide 3-b-N-acetylgalactosaminyltransferase or globoside synthase activity and the gene name changed to B3GALNT1 and its product renamed b3GalNAc-T1. This enzyme is responsible for the final step in the synthesis of the P antigen, the transfer of GalNAc to the terminal Gal of the Pk antigen. The final proof of this was the identification in 2002 by Hellberg et al. (3) of critical mutations in the B3GALNT1 gene as the genetic basis of P1k and P2k, the rare globoside-deficient null phenotypes of the GLOB system. Westman et al. (4) showed in 2015 that the same glycosyltransferase is responsible for PX2 antigen synthesis. In addition, 2019 Hagman-Ricci et al. (5) reported that the B antigen can be elongated by β3GalNAc-T1 to form the ExtB antigen. Thus, the system now comprises three antigens.","allele_notes":"","assignees":["Asa Hellberg"]},{"id":24,"isbt_number":24,"name":"Ok","symbol":"OK","category":"Blood Group System","approved":true,"version":4,"createdAt":"2024-04-29T09:32:30.165Z","updatedAt":"2025-09-24T11:11:38.191Z","description":"The OK blood group system consists of 3 antigens carried on a single pass type I membrane glycoprotein with 2 IgSF domains called Basigin (aka CD147, neurothelin, EMMPRIN). It consists of 248 amino acids and has a leader sequence of 21 amino acids, which is cleaved from the membrane bound protein.","allele_notes":"","assignees":["Yoshihiko Tani"]},{"id":32,"isbt_number":32,"name":"JR","symbol":"JR","category":"Blood Group System","approved":true,"version":2,"createdAt":"2024-04-29T09:32:34.319Z","updatedAt":"2025-09-24T11:11:40.569Z","description":"The JR blood group system consists of one antigen carried on a multipass membrane glycoprotein, ATP binding cassette subfamily G member 2 (ABCG2), also known as breast cancer resistance protein (BCRP) or CD338. ABCG2 consists of 655 amino acids, with a function of an ATP-dependent transporter with a highly diverse range of substrates. The glycoprotein is encoded by the ABCG2 gene, located on chromosome 4 (chr4:88,090,150-88,231,628; GRCh38/hg38).","allele_notes":"","assignees":["Vanja Crew"]},{"id":16,"isbt_number":16,"name":"Landsteiner-Wiener","symbol":"LW","category":"Blood Group System","approved":true,"version":5,"createdAt":"2024-04-29T09:32:25.363Z","updatedAt":"2025-09-24T11:13:47.717Z","description":"The LW blood group system consists of four antigens carried on a glycoprotein of 241 amino acids, ICAM-4, which belongs to the ICAM family of proteins. It has a leader sequence of 30 amino acids, and two I-set IgSF domains that characteristic of this family.","allele_notes":"","assignees":["Christine Lomas Francis"]}]