Distribution of human kappa locus IGKV2-29 and IGKV2D-29 alleles in Swedish Caucasians and Hong Kong Chinese

Polymorphism in the IGKV2-29 gene was shown to decrease the recombination f requency in B cells and to be important for immune responses to Haemophilus influenzae type b polysaccharide. By using the combination of PCR and rest riction enzyme mapping, the distribution of IGKV2D-29 and IGKV2-29 gene all eles was estimated in two geographically and ethnically different groups. W e found that V2D-29*01 homozygous individuals were most common in Swedish C aucasians (82%), but less common in the Chinese population of Hong Kong (28 %). The homozygous V2D-29*02 genotype was found in 19% Chinese, but only in one Caucasian (1%). The frequency of the heterozygous V2D-29*01/V2D-29*02 genotype was also higher in the Chinese population (46%) compared with the Caucasians (7%). V2-29*01 homozygosity was more frequent among Caucasians ( 85%) than among Chinese (19%). In contrast, homozygous V2-29*02 individuals were over-represented in the Chinese population (18%), whereas only one wa s found among Caucasians (1%). Heterozygous V2-29*01/V2-29*02 individuals w ere also more common in the Chinese (63%) than the Caucasian (15%) populati on. Most Caucasians had the combination of V20-29*01/V20-29*01 + V2-29*01/V 2-29*01 (74%), while the most common genotype for Chinese was V2D-29*01/V2D -29*02+V2-29*01/V2-29*02 (41%). Analysis of the association of V2D-29*02 an d V2-29*02 alleles demonstrated a high degree of linkage, as for V2D-29*01 with V2-29*01. These data show a significant difference in the distribution of IGKV2D-29 and IGKV2-29 alleles among Swedish Caucasians and Hong Kong C hinese. This may help to explain differences in the occurrence of H. influe nzae type b infection in the two populations. Evaluated methods for IGKV2D- 29 and IGKV2-29 allele detection can be used for the screening allele polym orphisms in other particular patient groups.