Table 1. Etiology of micropenis.

Hypogonadotropic hypogonadism

Kallman’s syndrome

Prader-Willi syndrome

Laurence-Moon syndrome

Bardet-Biedl syndrome

Rud’s syndrome

Other pituitary hormone deficiencies

Hypergonadotropic hypogonadism

Anorchia

Poly-X syndromes (ex: Klinefleter)

Gonadal dysgenesis

LH-receptor defects

Noonan’s syndrome

Trisomy 21

Robinow’s syndrome

Laurence-Moon syndrome

Bardet-Biedl syndrome

Defects in testosterone action

GH/IL-GH deficiency

Androgen receptor defect

5-a Reductase deficiency

Fetal Hydantoin Syndrome

Developmental abnormalities

Aphallia

Cloacal exstrophy

Idiopathic

Other congenital malformations

LH, luteinizing hormone; GH, growth hormone; IL-GH, insulin-like growth hormone.