Characterization of a complex chromosomal rearrangement in a patient with a typical catlike cry and no other clinical findings of cri-du-chat syndrome.

We report on the clinical, cytogenetic, and molecular cytogenetic findings in a 4-year-old girl who was evaluated for developmental delay and a catlike cry from birth. No other findings of cri-du-chat syndrome were present. Karyotype analysis demonstrated a de novo deletion and inverted duplication of the 5p region. The abnormality was confirmed and further defined by detailed FISH analysis using cosmid and lambda phage clones previously mapped to distinct regions of 5p. The analyses documented deletion of 5p15.3-->pter and an inverted duplication of 5p14-->5p15.3. The deleted segment on 5p contains the region implicated in the isolated catlike cry feature of the cri-du-chat syndrome, confirming that the genes involved in the catlike cry map to the distal end of 5p. Except for the catlike cry and possibly the developmental delay that may be due to the deletion of 5p, the duplication of 5p14-->5p15.3 in this patient did not present with additional anomalies. This study further demonstrates the usefulness of the molecular cytogenetic approach for characterizing complex chromosome rearrangements. Such analyses of patients with an isolated catlike cry can avoid an incorrect diagnosis of the cri-du-chat syndrome, which is associated with a more severe prognosis.