HAPPY MAPPING OF A YAC REVEALS ALTERNATIVE HAPLOTYPES IN THE HUMAN-IMMUNOGLOBULIN V(H) LOCUS

We have identified and sequenced 14 human immunoglobulin V(H) segments cloned in a yeast artificial chromosome, and have used a rapid PCR-ba sed technique (HAPPY mapping, 12) to derive the order and approximate distances between them. The sequences mapped comprise thirteen germlin e V(H) segments and one rearranged V(H)3 gene. Comparison of our map w ith other data suggests the existence of at least two distinct haploty pes, differing in the presence or absence of the consecutive genes DP- 78, DP-46 and DP-64, and in the duplication of segments DP-49 and DP-6 5. Screening of ten individuals confirms the existence of both haploty pes, and indicates that both are common amongst the population.