Autosomal dominant syndrome resembling Coffin-Siris syndrome

Coffin-Siris syndrome is a multiple congenital anomaly/mental retardation syndrome with phenotypic variability [OMIM 135900]. The diagnosis is based solely on clinical findings, as there is currently no molecular, biochemical, or cytogenetic analysis available to confirm a diagnosis. Although typically described as an autosomal recessive disorder, autosomal dominant inheritance has also been infrequently reported. We describe a mother and her two daughters who all have features that resemble Coffin-Siris syndrome. However, this is not a completely convincing diagnosis given that hypertelorism is not a feature of Coffin-Siris syndrome and the family is relatively mildly affected. Yet, this family provides further evidence of an autosomal dominant mode of inheritance for a likely variant of Coffin-Siris syndrome (at least in some families). In addition, Sibling 1 had premature thelarche. She is the second reported individual within the spectrum of Coffin-Siris syndrome to have premature thelarche, indicating that it may be a rare clinical feature.