Comparative genomic hybridisation in mentally retarded patients with dysmorphic features and a normal karyotype

Segmental aneusomy for small chromosomal regions has been shown to be a com mon cause of mental retardation and multiple congenital anomalies. A screen ing method for such chromosome aberrations that are not detected using stan dard cytogenetic techniques is needed. Recent studies have focused on detec tion of subtle terminal chromosome aberrations using subtelomeric probes. T his approach however excludes significant regions of the genome where submi croscopic rearrangements are also liable to occur. The aim of the present s tudy was to evaluate the efficiency of comparative genomic hybridisation (C GH) for screening of submicroscopic chromosomal rearrangements. CGH was per formed in a cohort of 17 patients (14 families) with mental retardation, dy smorphic features and a normal karyotype. Five subtle unbalanced rearrangem ents were identified in 7 patients. Subsequent FISH studies confirmed these results. Although no interstitial submicroscopic rearrangement was detecte d in this small series, the study emphasises the value of CGH as a screenin g approach to detect subtle chromosome rearrangements in mentally retarded patients with dysmorphic features and a normal karyotype.