The Noonan Syndrome: A Family Study

A family has been studied in which a man and four of his male adolescent children are affected with the Noonan syndrome. Four of the five family members have pulmonic stenosis confirmed by catheterization. Endocrine studies of the pituitary-gonadal axis in our patients suggest that the Noonan syndrome in the male can show normal gonadal function, primary abnormalities of the gonads, alteration in hypothalamic-hypophyseal function, or even some combination of these possibilities. The direct male-to-male transmission of the Noonan syndrome in this family strongly suggests that the condition is inherited in an autosomaldominant way. Hyperelastic skin and microscopic abnormalities of biopsied blood vessels suggest a basic defect in connective tissue in this disorder.