Chorioretinal dysplasia-microcephaly-mental retardation syndrome: another family with autosomal dominant inheritance

We describe a boy and his father with the chorioretinal dysplasia-microcephaly-mental retardation syndrome (CDMMS). Our report extends the phenotypic spectrum of autosomal dominant CDMMS by describing microphthalmia for the first time in an autosomal dominant family. The boy was also severely mentally retarded in contrast to the usual mild mental retardation in AD-CDMMS. Furthermore he had hypertonia, dysmorphic features and low body weight, which are uncommon in AD-CDMMS. CDMMS is a rare disorder. We traced 18 reports on CDMMS including 10 families, 6 with horizontal transmission and 4 with vertical transmission. There are 8 reports and observations on isolated cases with CDMMS. This might imply genetic heterogeneity with autosomal recessive and autosomal dominant inheritance, with a more severe clinical picture in the former but with quite variable inter- and intrafamilial expression. A review of the literature is given. The existence of autosomal recessive inheritance in families with so-called horizontal transmission is discussed as variable expression, reduced penetrance and germline mosaicism may also explain this condition. Careful (particularly ophthalmologic) examination of first degree relatives is necessary before genetic counseling is given.