Mapping of the HLA-D Region by Pulsed-field Gel Electrophoresis : Size Variation in the DQ-DR Interval

Pulsed field gel electrohporesis (PFGE) was used to construct genomic maps of different HLA-D region haplotypes. In the course of these experiments a new HLA class II β chain sequence, DVβ, was located close to DXα between DXα and DQβ. All other markers studied, from the DP, DZ/DO, DQ and DR subregions, were consistent in their positions in the haplotypes studied but the distance between DQα and DRα differed in various haplotypes. For example, in DR7 (MANN) this distance was approximately 380kb, but in the DR2 haplotype (AKIBA), it was 270kb. This may be due to variations, either in the number of duplicated DRB genes or in the length of other uncharted DNA, in the HLA-D region.