Rubinstein-Taybi syndrome (RTS) is a rare autosomal dominant genetic disorder 
and is characterized by mental retardation, distinctive facial features, broad 
and often angulated thumbs and great toes. We report on a 7 year old boy with 
classical Rubinstein-Taybi syndrome. His facial and clinical features were very 
typical, including broad thumbs with radial angulation and broad great toes. 
Rigorous genetic analysis of the CREBBP and EP300 genes using DNA sequencing and 
multiple ligation-dependent probe amplification (MLPA) revealed no causative 
mutation in this boy, only a hitherto unreported but paternally inherited 
heterozygous sequence alteration, c.506 1+9C>T in IVS 30-31, which most likely 
represents a normal variant (NetGene 2 splice prediction software). We question 
if this boy could have a hitherto undetectable mutation type.