Hypospadias is the second most common congenital defect of the male genitalia, after cryptorchidism. In USA, one in every 250 live births is estimated to be affected and the incidence seems to be increasing. The condition is characterized by the urethra opening on the underside of the penis, instead of at the tip. This condition is probably a result of a defect in the embryonal development of the urethra, between the 8th and 20th weeks of gestation. The condition is seen to be much more common in children of Jewish or Italian ethnicity.

Hypospadias can only be treated by surgical repair of the defect. The surgery involves using tissue grafts from either the foreskin or the inner lining of the mouth to reconstruct a proper urinary channel. Although this surgery can be performed at any age, it is best undertaken when the patient is between 3-18 months of age. Children who are left untreated generally have problems in properly using the toilet, and may, later in adulthood, have complications in performing sexual intercourse. Post-surgery, most patients lead a normal life. In a very minor number of cases, fistula may develop along the newly created channel, which may require further surgical correction.

A number of causes have been attributed to the development of hypospadias. Apart from environmental and endocrinal influences during development, there is also a genetic component to the development of this condition. This is exemplified by the increased incidence of hypospadias among monozygotic twins, as well as increased tendency for an affected father to have affected children. The exact genetic defect has not been identified to date. It is however, assumed that the condition follows a polygenic mode of inheritance.