Increased birth weight (>4 kg [8.8 lb]) and
length (>97th percentile), with normal adult height are typical.
Macrocephaly, macroencephaly, scaphocephaly, and delayed closure of
fontanelles. Intracranial manifestations include increased incidence of
intracranial tumors, hemangiomas, arteriovenous malformations, hemorrhage,
and seizure activity. Extracranial arteriovenous malformations occur.
Delayed psychomotor development with dyscoordination, myopathy, and
hypotonia. Intelligence may be normal or mildly retarded. Increased
salivation and drooling. Ophthalmologic features consist of strabismus
(exotropia), hypertelorism, and pseudopapilledema. High-arched palate.
Hashimoto thyroiditis has been reported in affected individuals. Pectus
excavatum. Juvenile intestinal polyposis with increased risk of
intussusception. Protein-losing enteropathy and hepatomegaly may occur.
Intestinal and skin lipomas tend to regress with age. Thumbs and great toes
are broad (clubbing). Skin manifestations include hemangiomas, multiple
lipomas, telangiectases, café-au-lait spots, facial acanthosis
nigricans-like discoloration, and cutis marmorata. Penis may be enlarged
with spotted pigmentation of the glans. Thyroid and breast tumors may be