A nonsense mutation of the ATRX gene causing mild mental retardation and epilepsy

Mutations in the X-encoded gene ATRX are known to give rise to profound syn dromal mental retardation (MR). Here, we describe a pedigree, including 4 a ffected family members with a 324C-->T nonsense mutation in the ATRX gene. Although 2 patients have moderate to profound MR and the typical facial fea tures of ATR-X syndrome, the other 2 patients presented with mild MR and ep ilepsy but without the characteristic facial dysmorphism. Mutations in the ATRX gene should be considered as a cause of mild MR in male patients lacki ng specific diagnostic features.