Testotoxicosis is a rare form of familial precocious puberty in boys with autossomal dominant inheritance. Secondary sexual features usually occur before 4 years of age. In this condition, testosterone are elevated with suppressed or prepubertal gonadotropin levels. Several germline activating mutations in exon 11 of the LH receptor gene have been described in boys with testotoxicosis. The molecular analysis of 8 Brazilian boys with testotoxicosis revealed 5 different mutations, 3 of them identified exclusively in Brazil: Ala568Val, Leu457Arg, and Leu368Pro, located in the third intracellular loop and in the III and I transmembrane helices, respectively. The Ala568Val mutation was found in 42.8% of the Brazilian families. Women with activating mutations, mother or sisters of boys with testotoxicosis, did not develop precocious puberty and showed normal reproductive function. Two Brazilian women, including a prepubertal girl with activating mutations, were asymptomatic and had normal hormonal profile. Somatic activating mutations of the LH receptor gene were recently identified in 3 boys with Leydig cell tumors. However, a recent report did not find such mutations in 4 Leydig tumors, 3 tecomas and 4 Sertoli-Leydig tumors. In conclusion, germline and somatic activating mutations of the LH receptor gene cause male precocious puberty and Leydig cell tumors, respectively. In constrast, similar mutations in females do not cause any abnormal phenotype.
Precious puberty; LH; Receptor; Gonadal tumors
