Pubertal development in patients with McCune-Albright syndrome or pseudohypoparathyroidism.

ABSTRACT

Gain or loss of function mutations of the GNAS1 gene lead to McCune-Albright syndrome (MAS) or pseudohypoparathyroidism Ia (PHP-Ia), respectively. Patients with MAS, caused by a post-zygotic missense mutation leading to constitutive activation of Gs alpha, suffer from gonadotropin-independent precocious puberty, and delayed or incomplete sexual development and reproductive dysfunction is found in women with PHP-Ia, an inherited disorder caused by deficient expression or function of the Gs alpha protein. In females with MAS, 50% developed precocious puberty by the age of 4 years, the remaining between 4 and 8 years. Peripheral precocious puberty is often atypical and characterized by alternate periods of rapid progression and regression of pubertal development; menstrual bleeding may occur before breast development. Ovarian cyst growth and regression is often described as a sign of ovarian follicle hyperactivation. Notwithstanding this clinical heterogeneity, a subset of patients with MAS develop relentlessly progressive precocious puberty ultimately resulting in premature epiphyseal fusion and reduced adult stature. Long-term information on reproductive function has been obtained in females some patients had regular menses without ovarian cysts on pelvic US scan, whereas others were oligomenorrheic and showed recurrent ovarian cysts. In males with MAS, precocious puberty occurred in three patients between 4 and 9 years of age. In one patient, long-term follow-up demonstrated normal plasma testosterone and gonadotropin values at the age of 17 years. On testicular sonography, multiple hyperechogeneic spots were found in both testicles (snow-storm appearance). Female patients with PHP-Ia were oligomenorrheic or amenorrheic; more than half had delayed or incomplete sexual development, They were mildly hypoestrogenic with normal to slightly elevated serum gonadotropin levels. These clinical and biochemical findings indicate partial resistance of the theca and granulosa cells of the ovary to gonadotropins due to deficient Gs alpha activity. Responsiveness might be sufficient to promote some degree of follicular development and steroid secretion, but insufficient to induce ovulation