Characterization of genomic polymorphism of an activation-associated antigen, Blast-1.

Blast-1 is a human activation-associated glycoprotein expressed on the surface of mononuclear cells, and a possible genetic marker for the manifestation of rheumatoid arthritis. In the present study, genomic polymorphism of the Blast-1 gene was analyzed using 100 healthy subjects. Restriction fragment length polymorphism (RFLP) of the Blast-1 gene was recognized only by Bam HI digestion among 46 restriction enzymes tested. The sizes of polymorphic fragments were 2.4 kilobase (kb) on the L band, and 1.9 kb on the S band. A family study demonstrated that the two alleles of the Blast-1 gene were inherited in a co-dominant Mendelian fashion. The genotype frequencies of homozygosity for the L and S bands were 47% and 42%, respectively, while the frequency of heterozygosity was 11%. The allele frequencies of the L and S bands were 0.68 and 0.32, respectively. The distribution of the Blast-1 genotypes in the present study was concordant with Hardy-Weinberg equilibrium (p greater than 0.7), which indicates that the frequency of the Blast-1 gene in the population is derived from random mating in preceding generations. The results of the present study may provide useful information in disease associations with the Blast-1 gene.