5 NOVEL GENES FROM THE CRI-DU-CHAT CRITICAL REGION ISOLATED BY DIRECTSELECTION

Cri-du-chat is a well described partial aneusomy resulting from deleti on of the short arm of chromosome 5. The hallmark clinical feature of cri-du-chat, a high-pitched monochromatic cry, has recently been local ized to 5p15.3, separate from the remaining clinical features of the s yndrome, which have been localized to 5p15.2. Five chromosome and spec ific probes from the latter region, designated the cri-du-chat critica l region (CDCCR), were used to isolate 30 cosmids from the LANL chromo some 5 specific cosmid library. The 30 framework cosmids were used in a direct selection with three cDNA sources to isolate an initial set o f expressed sequences. Nine unique cDNAs were found that hybridized to four discrete sets of cosmids in the CDCCR. The nine cDNAs are novel by sequence database comparisons, and conservatively represent four tr anscription units. More recently, we have also constructed a YAC conti g of the CDCCR which spans approximately 2 Mb. As expected, ESTs deriv ed from the nine novel cDNAs map back to the contig. Limited expressio n profiles of these cDNAs have been obtained. Two cDNAs that map to on e discrete set of cosmids have different expression patterns, suggesti ng that they represent two different genes and increasing the number o f putative genes to five. Further characterization of these genes and the estimated 100 additional genes deleted in cri-du-chat should lead to better diagnostic markers and an understanding of the molecular mec hanisms of the disease.