Dysmorphology and mental retardation: molecular cytogenetic studies in dysmorphic mentally retarded patients

In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 18 patients (16 males and 2 females) with dysm orphic features were selected to perform FISH studies by using subtelomeric probes to discover cryptic terminal deletions or duplications, undetectabl e with standard banding techniques. In the 13 investigated patients, no abn ormalities were found with a selected battery of subtelomeric probes. The r esults of cryptic chromosomal rearrangement studies are variable but the fr equency of positive diagnostic findings seems to be lower than previously e xpected. (C) 2001 Editions scientifiques et medicales Elsevier SAS.