Detection of a BAC clone duplication in 17p11.2 in two unrelated patients, affected by severe epileptic encephalopathy, by genome array CGH: a new variant of Potochy-Lupsky syndrome?

The duplication 17p11.2 syndrome, associated with dup(17)(p11.2p11.2), is a recently recognized syndrome of multiple congenital anomalies and mental retardation. It was the first described reciprocal micro-duplication syndrome that was predicted to be a reciprocal of a micro-deletion syndrome. It is the reciprocal of the Smith–Magenis syndrome caused by a micro-deletion of the same segment on 17p (Potocky et al. 2007). We report a novel pathological variant of this syndrome, detected by genome array-CGH, in two unrelated subjects with dup(17)(p11.2p11.2), The array analysis was performed using the BAC Cyto-chips Blue-Gnome platform, at 0.5-Mb median resolution, and revealed the presence of the same BAC duplication in both patients. Fluorescence in situ hybridization analysis with the same BAC did not resolve the duplication. The duplicated BAC (RP11-78O7), of about 140 K, maps in 17p11.2 and contains an interesting gene, presumably involved in the pathology. The parents did not show the duplication, suggesting that it was a de novo rearrangement. Cytogenetic and clinical features of subjects with partial trisomy of proximal 17p have been described, mostly in isolated case reports or literature reviews. These nonspecific and non-characteristic findings include developmental delay, mental retardation and dysmorphic features. Our patients present a particular form of epileptic encephalopathy associated with severe mental retardation and autistic behaviour. Molecular and genetic studies are in progress to define and characterize the rearrangement and for better genotype/phenotype correlation