A provisionally unique syndrome of macrosomia, bone overgrowth, macrocephaly, and tall stature.

We report a young man with intrauterine macrosomia, macrocephaly, and bony abnormalities. Excessive growth continued throughout infancy and childhood. Bone age was advanced. He developed contractures of the large joints and was confined to a wheelchair. Extensive laboratory studies, repeated on multiple occasions were all normal. Intellectually, he was normal. His near final height was 234 cm. The constellation of findings in this patient is at variance with previously described syndromes of tall stature. We postulate that excessive size and bone overgrowth in this young man is caused by a receptor/post-receptor abnormality involving a growth on/off mechanism at the cellular level.