Posterior urethral valves in siblings

The etiology and incidence of posterior urethral valves is unknown. We report on a pair of non-twin siblings with identical pathology stemming from type I posterior urethral valves as well as discordance in a pair of monozygotic twins. Familial posterior urethral valves have been reported before in both twin and non-twin siblings. The occurrence of identical pathology in non-twin siblings suggests the possibility of an inherited trait as does its occurrence in identical twins. However, non-identical clinical manifestation is as common as is identical presentation in both groups. There are also instances of discordance in monozygotic twins suggesting the possibility of a random mutation. As such, we recommend urologic evaluation of the male siblings of affected patients with posterior urethral valves. Further prospective and retrospective analyses are needed to define the genetic etiology of valves.