UCL Discovery

Abstract

The Rubinstein-Taybi syndrome (RTS; OMIM 180849) is a well-defined mental retardation/multiple congenital anomalies (MR/MCA) syndrome characterized by postnatal growth retardation, microcephaly, specific facial features, broad thumbs and halluces, and MR of variable degree. Ten percent of patients with RTS have a microdeletion 16p13.3, 40-50% carry a mutation of the CREBBP gene and another 3% have a mutation in the EP300 gene. In the remaining patients with clinically suspected RTS no mutation can be detected. Here we describe two patients with an RTS phenotype, one with a mutation in the CREBBP gene and the other without a detectable CREBBP or EP300 mutation and without a chromosomal imbalance on high-resolution arrays. Both patients present with the characteristic facial RTS phenotype, broad thumbs and big toes, mild MR, formation of keloids and glaucoma, but without postnatal growth retardation or microcephaly. In addition, they have both congenital camptodactyly of third (and fourth) fingers, which has not reported in RTS previously. We suggest that they represent a clinical subtype of RTS.