Central precocious puberty
Central precocious puberty is a condition causing sexual development to begin significantly earlier than the normal age range.
Overview
Puberty typically begins between ages 8 and 13 in girls and 9 and 14 in boys. In central precocious puberty, these signs appear before age 8 in girls and age 9 in boys. Symptoms include the development of pubic and underarm hair, growth spurts, acne, and body odor. Girls may develop breasts and begin menstruation, while boys may experience growth of the penis and testes and voice deepening.
While affected children may be taller than their peers initially, they may stop growing early, potentially resulting in shorter adult stature. The condition can also cause psychological and behavioral challenges due to early development.
Causes
The most common known genetic cause is a mutation in the MKRN3 gene. Puberty is triggered when the hypothalamus releases gonadotropin-releasing hormone (GnRH). The MKRN3 protein normally acts to inhibit this release, effectively holding off puberty. Mutations in MKRN3 lead to a nonfunctional protein, allowing the hypothalamus to release GnRH prematurely.
The MKRN3 gene is subject to genomic imprinting, meaning its activity depends on which parent it was inherited from. Only the copy inherited from the father is active. Consequently, the condition is typically inherited from the father.
Inheritance
Central precocious puberty follows an autosomal dominant pattern, meaning one copy of the altered gene is sufficient to cause the disorder. In familial cases, the mutation is inherited from the father. If a father carries the mutation, he may pass it to his sons and daughters. Some individuals with the mutation may not show signs of the condition, and cases can also occur sporadically without a known family history.