Construction of cosmid/BAC contigs for the cat eye syndrome chromosome region (22ql 1)

Cat eye syndrome (CES) is caused by tetrasomy (or trisomy) of the 22ql 1. The morphological anomalies in CES include coloboma of the eye, imperforate anus and characteristic heart malformation (totally anomalous pulmonary venous return). Most (>90%) of the CES patient has a supernumerary bisatellited marker chromosome (mar) retaining two copies of the 22pter-ql 1 region. We have constructed cosmid/BAC contigs of CES chromosomal region to isolate the disease-causing genes. We previously prepared a CES region-specific cosmid library (9,200 clones, 10 times equivalent) with flow-sorted marker chromosomes of CH91-157 cell line established from a CES patient. Cosmid clones derived from the long arm were selected by fluorescence in situ hybridization (FISH) and 7 STS's were established to screen CEPH YAC library (35,000 clones). Twenty YAC clones were identified and arrayed into a YAC contig. Using these YAC clones as probes we screened the CES region-specific cosmid library and a human genomic BAC library (70,000 clones, 2.3 times equivalent) that we recently constructed, and 1,131 cosmids and 18 BAC clones were obtained. These cosmid/BAC clones were analyzed by finger printing and hybridization to build cosmid/BAC contigs. So far, 3 contigs including one with an approximate size of 350 kb have been made. These cosmid/BAC clones will be used for the large scale genomic sequencing.