Cloning the human major histocompatibility complex in YACs

To clone the human major histocompatibility complex (MHC), 53 YACs, with an average size of 490 kb, were isolated and characterized from the CEPH YAC library. These YACs were organized in a single large contig covering more than 4000 kb. Furthermore, a complete physical map of the previously uncloned HLA class I region was established from partial and/or total digestions of 15 YACs spanning 2000 kb. This resulted in the establishment of the first YAC contig that spans the entire MHC region and constitutes an essential step in the isolation of all of the genes present in the region.