Cri-du-chat is a well described partial aneusomy resulting from deletion of the 
short arm of chromosome 5. The hallmark clinical feature of cri-du-chat, a 
high-pitched monochromatic cry, has recently been localized to 5p15.3, separate 
from the remaining clinical features of the syndrome, which have been localized 
to 5p15.2. Five chromosome 5-specific probes from the latter region, designated 
the cri-du-chat critical region (CDCCR), were used to isolate 30 cosmids from 
the LANL chromosome 5 specific cosmid library. The 30 framework cosmids were 
used in a direct selection with three cDNA sources to isolate an initial set of 
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 transcription units. 
More recently, we have also constructed a YAC contig of the CDCCR which spans 
approximately 2 Mb. As expected, ESTs derived from the nine novel cDNAs map back 
to the contig. Limited expression profiles of these cDNAs have been obtained. 
Two cDNAs that map to one discrete set of cosmids have different expression 
patterns, suggesting that they represent two different genes and increasing the 
number of 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 mechanisms of the 
disease.