The cri-du-chat syndrome is a well-described partial aneusomy resulting from the deletion of the short arm of chromosome 5. Patients with this syndrome present with microcephaly, a round face, hypertelorism, micrognathia, prominent nasal bridge, epicanthal folds, hypotonia, and severe psychomotor and mental retardation. Through the characterization of over 50 patients with 5p deletions, a chromosomal region that is 2 Mbp in 5p15.2 and the chromosomal segment involved in the cat-like cry has been mapped to a 750 region of 5p15.3 YAC contigs of both regions have been completed and nonchimeric YACS that span each region have been identified. While the long term goal of this proposal is to identify genes that, when present in one copy, cause the clinical features associated with the cri-du-chat syndrome, the initial goal will be to develop a transcriptional map of the region in order to identify candidate genes based on their location with respect to the cri-du-chat critical regions. The strategy to identify these genes is first to continue with the characterization of patients with small 5p deletions or partial cri-du-chat phenotypes such that the two critical regions can be further narrowed. Second, the construction of a cosmid contig which has been initiated will be completed. Third, several approaches to identify the genes mapping within the critical regions will be performed and include EST mapping, cDNA selection, exon-trapping and cloning HTF islands. After performing screening strategies to identify clones that are derived from the same gene, the pattern of expression of unique genes will be investigated. This investigation will include investigating the level of expression in human adult and fetal tissues as well as the level of expression in different murine gestational stages. The initial characterization of these genes will identify candidate genes that may be involved in the clinical etiology of the cri-du-chat syndrome based on whether a gene is expressed during fetal development.
