The Organization of the γ-Glutamyl Transferase Genes and Other Low Copy Repeats in Human Chromosome 22q11

A clone map consisting of YACs, cosmids, and fosmids has been constructed covering low copy repeat regions of human chromosome 22q11. A combination of clone restriction digest analysis, single-copy landmark content analysis, Hin dIII– Sau 3AI fingerprinting, and sequencing of PCR products derived from clones was required to resolve the map in this region. Seven repeat-containing contigs were placed in 22q11, five containing γ-glutamyl transferase (GGT) sequences described previously. In one case, a single interval at the resolution of the YAC map was shown to contain at least three GGT sequences after higher resolution mapping. The sequence information was used to design a rapid PCR/restriction digest technique that distinguishes the GGT loci placed in the YAC map. This approach has allowed us to resolve the previous cDNA and mapping information relating to GGT and link it to the physical map of 22q11. [The sequence data described in this paper have been submitted to EMBL under accession nos. Z93342 (gene 11; EMBL identification no. HSGGT11), Z93343 (gene 12; EMBL no. HSGGT12), Z93344 (gene 1; EMBL no. HSGGT1A), Z93345 (gene 2; EMBL no. HSGGT2A), Z93346 (gene 3; EMBL no. HSGGT3A), Z93347 (gene 3-like; EMBL no. HSGGT3L), and Z93348 (gene 6; EMBL no. HSGGT6).]