Phakomatoses are a group of neurocutaneous disorders characterised by involvement of structures that arise from the embryonic ectoderm (thus central nervous system, skin and eyes). Other organs may also be involved

mental retardation: up to half have normal intelligence

adenoma sebaceum: only present in about 3/4 of patients ⁶

The full triad is only seen in a minority of patients (around 30%). Therefore, diagnostic criteria have been developed to aid the diagnosis of TS - see tuberous sclerosis diagnostic criteria. When patients do not meet these criteria they are sometimes referred to as manifesting a forme fruste of the condition. 

Pathology

Spontaneous mutations account for 50-86% of cases ⁴, with the remainder inherited as an autosomal dominant condition. In the majority of such cases (80%) the mutation has been narrowed down to two tumour suppressor genes :

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