Review Question - QID 106534

The image of the boy depicts an ash leaf spot, characteristic of tuberous sclerosis (TS). The image of the father depicts adenoma sebaceum, also seen in TS, which is an autosomal dominant disorder.

TS is a neurocutaneous disorder characterized by widespread hamartomas in the CNS, skin, and viscera. TS is also associated with cardiac rhabdomyomas, renal angiomyolipomas, subependymal giant cell astrocytomas, seizures, and sebaceous adenomas (pictured on the father's face). TS is an autosomal dominant disorder. Notably, the disorder is believed to have complete penetrance, although it has variable expressivity.

Hurst and Wilcoski review the presentation of TS. TS affects about 1 in 10,000 people in the general population. It is believed to occur in about 1 in 6,000 live births. It is the second most frequent neurocutaneous syndrome, with neurofibromatosis being the most common. TS does not have any predilection for affecting a particular race or gender. Intelligence is frequently normal, but may be decreased in patients affected by seizures.

Krueger and Northrup review the genetics of TS. Two genes are known to be involved in the development of the disease: TSC1 and TSC2. TSC1 codes for hamartin, and TSC2 codes for tuberin. These two proteins form a complex that is involved in regulating mTORC1, which is important in intracellular growth signalling via inhibition of a small GTPase ras homolog.

Figure A depicts an ash leaf spot, characteristic in TS. Figure B depicts adenoma sebaceum, a common facial finding in TS. Illustration A depicts a subependymal nodule, characteristic in TS. Illustration B depicts an ungual fibroma, also common in TS.

Incorrect Answers:
Answer 1: Neurofibromatosis is a hereditary disorder presenting with multiple nerve sheath tumors and cafe-au-lait spots, not ash leaf spots.

Answer 2: Von Hippel-Lindau characteristically presents with hemangioblastomas, angiomatosis, and often later leads to renal cell carcinoma.

Answer 3: Familial adenomatous polyposis includes adenomatous polyps that develop after puberty in the colon.

Answer 5: Osler-Webber-Rendu is a disorder of blood vessels, involving telengiectasias and recurrent epistaxis.