The Polymorphism of SMIM1 Gene in Chinese Dividuals

The SMIM1 gene, which encodes the high-frequency blood group antigen Vel, has not been systematically analyzed at the molecular level in Chinese individuals. To better understand the SMIM1 genetic polymorphism, we assessed mutations among healthy Chinese individuals, patients with red blood cell autoantibodies and hematological disease. A total of 130 patients with hematological disease (case I group), 50 patients with red blood cell autoantibodies (case II group), and 500 healthy controls (control group) were enrolled. Exons 3 and 4 in the SMIM1 gene were sequenced to identify genetic variants or mutations. A polyclonal anti-Vel antibody was used to evaluate the expression of the Vel antigenon red blood cells in patients with novel alleles. The novel alleles of the SMIM1 gene were intron 3 position 193 (TT, CT, CC), 194 (GG, AG), 3′ untranslated region positions 81 (CC, CA) and 87 (AA, CA). The single nucleotide polymorphism (SNP) frequencies of intron 3 position 193 TT, CT, CC were 13.1, 39.2, 47.7% in case group I, 6.7, 33.3, 60.0% in case group II and 8.5, 35.6, 56.2% in the control group, respectively. Other minor allele frequencies were all greater than 10% and all SNPs in Chinese showed Vel antigen expression on RBC membranes. The allele at intron 3 position 193 was the most frequent mutant allele found in the Chinese population and Vel antigen deficiency may not cause problems in Chinese patients with hematological diseases and RBC autoantibodies.