The polymorphism of Knops blood group system in Korean population and their relationship with HLA system

The main purpose of this report is to provide baseline gene frequencies of Knops blood group in the complement receptor 1 gene (CR1) in Korean population. In addition, possible relationship between the CR1 polymorphism and HLA specificities were studied, because the two systems had principal importance in immunity. CR1, which contains Knops antigens, was investigated by PCR-direct sequencing from 238 cord blood from Koreans. HLA data was archived from the enrolled cord blood units. Among the 7 SNPs, only 4843 (for KCAM antigen) and 4223 (for Yk(a)) nucleotide positions showed polymorphism. The genotype frequencies of KCAM were A/A (62.2%), A/G (33.2%), and G/G (4.6%); Yk(a) were C/C (29.4%), C/T (50%), and T/T (20.6%). KCAM (A/A) associated with HLA-DRB1(∗)13 (p=0.003, P(c)=0.0513); KCAM (G/G) with HLA-A(∗)30 (p<0.001, P(c)=0.0012). The Knops blood group system in Korean population has no diversity, except SNPs for KCAM and Yk(a), and the genotype of KCAM related with specific HLA alleles.