Cri-du-chat syndrome is caused by haploinsufficiency of the genes on the distal 
part of the short arm of chromosome 5, and characteristic features include 
microcephaly, developmental delays, and a distinctive high-pitched mewing cry. 
Most cri-du-chat syndrome cases result from a sporadic de novo deletion that is 
associated with a low recurrence risk. On rare occasions, however, cri-du-chat 
syndrome with 5p monosomy can be accompanied by 5q trisomy. This combination is 
virtually always associated with parental large pericentric inversions. Among 
previously reported cri-du-chat syndrome cases with 5p monosomy accompanied by 
5q trisomy, the aneusomy of chromosome 5 in all but one case was cytogenetically 
visible using G-banding. When an accompanying 5q trisomy is detected, a 
significant recurrence risk is expected. We here report on a patient with 
cri-du-chat syndrome phenotype who initially exhibited a normal karyotype on 
G-banding but in whom molecular analysis using multiplex ligation-dependent 
probe amplification and array comparative genomic hybridization revealed a 5p 
deletion accompanied by a 5q duplication. Parental chromosomal testing led to 
the identification of a very large pericentric inversion, of which breakpoints 
resided at the terminal regions of 5p15.31 and 5q35.1. This information was 
vital for counseling the family regarding the significantly high recurrence 
risk.