Epilessia generalizzata e ritardo mentale di grado lieve associata a larga duplicazione-inversione del cromosoma 15 = Mild generalized epilepsy and developmental disorder associated with large Inv Dup(15)

Patients with large inverted duplication of chromosome 15 InvDup(15), including the Prader-Willi/Angelman region, usually display severe mental retardation and epilepsy. We report two patients with InvDup(15) whom, in spite of a large duplication, presented with a mild phenotype including adult onset epilepsy. The discrepancy between the mild phenotype and the severe chromosomal abnormality detected in these two patients further supports the notion that the site of breakpoint might be contributory to the InvDup(15) phenotype. It also suggests that such a diagnosis should be considered in atypical cases of generalized epilepsy of adult-onset without clear-cut etiology.