title: Homozygosity for a null allele of SMIM1 defines the Vel-negative blood group phenotype.
abstract: The Vel antigen is present on red blood cells (RBCs) from all humans except rare Vel-negative individuals who can form antibodies to Vel in response to transfusion or pregnancy. These antibodies may cause severe hemolytic reactions in blood recipients. We combined SNP profiling and transcriptional network modeling to link the Vel-negative phenotype to SMIM1, located in a 97-kb haplotype block on chromosome 1p36. This gene encodes a previously undiscovered, evolutionarily conserved transmembrane protein expressed on RBCs. Notably, 35 of 35 Vel-negative individuals were homozygous for a frameshift deletion of 17 bp in exon 3. Functional studies using antibodies raised against SMIM1 peptides confirmed a null phenotype in RBC membranes, and SMIM1 overexpression induced Vel expression. Genotype screening estimated that ~1 of 17 Swedish blood donors is a heterozygous deletion carrier and ~1 of 1,200 is a homozygous deletion knockout and enabled identification of Vel-negative donors. Our results establish SMIM1 as a new erythroid gene and Vel as a new blood group system.
authors.affiliation: Hematology and Transfusion Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden. jill.storry@med.lu.se
authors.forename: Jill R
authors.initials: JR
authors.lastname: Storry
authors.forename: Magnus
authors.initials: M
authors.lastname: Jöud
authors.forename: Mikael Kronborg
authors.initials: MK
authors.lastname: Christophersen
authors.forename: Britt
authors.initials: B
authors.lastname: Thuresson
authors.forename: Bo
authors.initials: B
authors.lastname: Åkerström
authors.forename: Birgitta Nilsson
authors.initials: BN
authors.lastname: Sojka
authors.forename: Björn
authors.initials: B
authors.lastname: Nilsson
authors.forename: Martin L
authors.initials: ML
authors.lastname: Olsson
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001789:Blood Group Antigens / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D059472:Exome / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D017353:Gene Deletion; D020869:Gene Expression Profiling; D053263:Gene Regulatory Networks; D015894:Genome, Human; D006720:Homozygote; D006801:Humans; D007518:Isoantibodies / Q000276:immunology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010375:Pedigree; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011247:Pregnancy; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000235:genetics
chemical_list: D015415:Biomarkers; D001789:Blood Group Antigens; D007518:Isoantibodies; D008565:Membrane Proteins
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