Fortuitous FISH diagnosis of an interstitial microdeletion (5)(q31.1q31.2) in a girl suspected to present a cri-du-chat syndrome.

Constitutional interstitial deletions of 5q are relatively rare and most are poorly characterized cytogenetically. Consequently a definite karyotype-phenotype correlation is difficult to establish. We report on a new case of a girl presenting with an abnormal cry, upslanting palpebral fissures, hypertelorism, anteverted nostrils, microretrognathia, growth retardation, and an adenoid cyst at the base of the tongue. The first suspected diagnosis was cri-du-chat syndrome because of the mewing cry. Standard cytogenetic analyses were interpreted as normal, but FISH studies using the probe of cri-du-chat syndrome with the control probe EGR1 (5q31.2)/D5S23 (Abbott) revealed a 5q31.2 microdeletion which was then confirmed by CGH-array (Abbott). FISH studies using PACs and BACs clones (Rocchi, Italia) enabled us to characterize the breakpoints of the deleted region. Cytogenetic analysis with FISH studies revealed a normal karyotype with normal 5q31 region in both parents. This case is compared with the other cases reported in the literature.