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.