Familial hydrocephalus with a low-insertion umbilicus.

Two brothers, age 16 months and 3 years, had a seemingly unique combination of hydrocephalus of the lateral ventricles and a low-insertion umbilicus. Both had similar mildly unusual facies and inguinal hernias; one had unilateral cryptorchidism. The older brother had tetralogy of Fallot, and the younger had mildly enlarged, echogenic kidneys with vesicoureteral reflux. Neither boy had adducted thumbs, pyramidal tract signs, or significant developmental delay. A review of the literature on familial hydrocephalus found no similar cases. A low-set umbilicus is not a frequently noted anomaly; its embryology and associated syndromes are discussed. The association of hydrocephalus and a low-set umbilicus appears to be the manifestation of a monogenic disorder in this family, and could be inherited in either an autosomal recessive or X-linked recessive manner.