MedGen

Early activation of the hypothalamic-pituitary-gonadal axis results in gonadotropin-dependent precocious puberty, also known as central precocious puberty, which is clinically defined by the development of secondary sexual characteristics before the age of 8 years in girls and 9 years in boys. Pubertal timing is influenced by complex interactions among genetic, nutritional, environmental, and socioeconomic factors. The timing of puberty is associated with risks of subsequent disease: earlier age of menarche in girls is associated with increased risk of breast cancer, endometrial cancer, obesity, type 2 diabetes, and cardiovascular disease. Central precocious puberty has also been associated with an increased incidence of conduct and behavior disorders during adolescence (summary by Abreu et al., 2013). Genetic Heterogeneity of Central Precocious Puberty Central precocious puberty-2 (CPPB2; 615346) is caused by mutation in the MKRN3 gene (603856) on chromosome 15q11. [from OMIM]

Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the presence of low circulating concentrations of sex steroids. IGD is associated with a normal sense of smell (normosmic IGD) in approximately 40% of affected individuals and an impaired sense of smell (Kallmann syndrome) in approximately 60%. IGD can first become apparent in infancy, adolescence, or adulthood. Infant boys with congenital IGD often have micropenis and cryptorchidism. Adolescents and adults with IGD have clinical evidence of hypogonadism and incomplete sexual maturation on physical examination. Adult males with IGD tend to have prepubertal testicular volume (i.e., <4 mL), absence of secondary sexual features (e.g., facial and axillary hair growth, deepening of the voice), decreased muscle mass, diminished libido, erectile dysfunction, and infertility. Adult females have little or no breast development and primary amenorrhea. Although skeletal maturation is delayed, the rate of linear growth is usually normal except for the absence of a distinct pubertal growth spurt. [from GeneReviews]