Cri-du-chat is a chromosomal deletion syndrome characterized by partial deletion 
of the short arm of chromosome 5. The clinical symptoms include growth and 
mental retardation, microcephaly, hypertelorism, epicanthal folds, hypotonia, 
and a high-pitched monochromatic cry that is usually considered diagnostic for 
the syndrome. Recently, a correlation between clinical features and the extent 
of the chromosome 5 deletions has identified two regions of the short arm that 
appear to be critical for the abnormal development manifested in this syndrome. 
Loss of a small region in 5p15.2 correlates with all of the clinical features of 
cri-du-chat with the exception of the cat-like cry, which maps to 5p15.3. Here 
we report the construction of a YAC contig that spans the chromosomal region in 
5p15.2 that plays a major role in the etiology of the cri-du-chat syndrome. YACs 
that span the 2-Mb cri-du-chat critical region have been identified and 
characterized. This YAC contig lays the groundwork for the construction of a 
transcriptional map of this region and the eventual identification of genes 
involved in the clinical features associated with the cri-du-chat syndrome. It 
also provides a new diagnostic tool for cri-du-chat in the shape of a YAC clone 
that may span the entire critical region.