Discordance of congenital bilateral anorchia in uniovular twins: 17 years of observations on growth and development.

We have reported observations of growth and development made over a 16-year period on a subject who suffered bilateral congenital anorchia and his uniovular twin brother. The anorchic individual was treated with oxandrolone for a period of 3.6 years prior to the testosterone replacement therapy. The oxandrolone therapy produced a significant increment in the height age without excessive gain in bone age. At the age of 20.9 years the anorchic twin is 5.4 cm taller than his normal twin. Other differences observed between the twins reported here include the following: the anorchic subject had longer extremities, greater biacromial and biiliac distances and a smaller penis than his normal sibling. Oxandrolone therapy does appear to modify the ultimate height in children.