Nonsyndromal overgrowth in males with mild psychomotor delay.

Over the last 3 years we ascertained 42 patients for statural overgrowth and/or macrocephaly, who also had mild developmental delay. There were 39 males and three females, two of whom were sisters. In no case was tall stature a familial characteristic. Family history was unremarkable, except for the case of the two sisters. Physical examination did not demonstrate any consistent pattern of malformations or anomalies identifying a syndrome, known or unknown. Chromosomes were apparently normal and the molecular test for the fragile X syndrome yielded normal results in all cases. Muscular hypotonia, advanced bone age, and epilepsy were relatively consistent manifestations. The hypothalamus-pituitary axis seemed to be intact when tested through the blood levels of insulin-like growth factors I and II and of the insulin-like growth binding protein 3, and the excess of growth was apparently growth hormone independent. The condition comprising excessive growth, developmental delay, muscular hypotonia, absence of a consistent pattern of physical anomalies, and apparently sporadic occurrence, largely limited to males, may be heterogenous.