A novel missense mutation in the GTPase activating protein homology region of TSC2 in two large families with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder (OMIM 191092) characterised by autism, seizures, mental retardation, benign tumours of the brain, heart, kidney, lung, and skin, and malignant tumours of the kidney. 1 TSC has a wide range of phenotypic variability, with some subjects severely affected and others only mildly affected. [...]we anticipate that these families will be important in the future identification of modifier gene effects in TSC.