NEW HLA-DPB1 ALLELES GENERATED BY INTERALLELIC GENE CONVERSION DETECTED BY ANALYSIS OF SPERM

The rate at which allelic diversity at the HLA loci evolves has been t he subject of considerable controversy. The patchwork pattern of seque nce polymorphism within the second exon of the HLA class II loci, part icularly in the DPB1 locus, may have been generated by segmental excha nge (gene conversion). We have analysed the frequency of variant DPB1 sequences that have been created by interallelic gene conversion in th e germline by screening pools of sperm using PCR amplification and oli gonucleotide probe typing. Our results indicate that-about 1/10,000 sp erm represents a new DPB1 sequence generated by short tracts of segmen tal exchange (gene conversion) within the second exon, suggesting that interallelic gene conversion may have an important role in generating the extensive allelic diversity at the HLA loci.