**Core Concept**
Familial male limited precocious puberty (FMPP) is a rare condition characterized by early onset of puberty in boys, typically before the age of 9. It is caused by mutations in the gene encoding the androgen receptor, leading to abnormal androgen signaling and subsequent pubertal development.

**Why the Correct Answer is Right**
FMPP is caused by mutations in the androgen receptor gene (AR), which codes for the androgen receptor protein. This protein is responsible for mediating the effects of androgens, such as testosterone, on various tissues. In FMPP, the mutated androgen receptor protein is unable to properly bind and respond to androgens, resulting in precocious puberty. The condition is inherited in an X-linked recessive pattern, meaning that the gene responsible for the condition is located on the X chromosome.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, but it would be incorrect if it stated that FMPP is caused by an increase in gonadotropin-releasing hormone (GnRH) secretion. While GnRH levels do increase during puberty, the underlying cause of FMPP is a genetic mutation in the androgen receptor gene, not an increase in GnRH.

**Option B:** This option is not provided, but it would be incorrect if it stated that FMPP is characterized by delayed bone age. In fact, boys with FMPP typically exhibit accelerated bone age, which is a hallmark of the condition.

**Option C:** This option is not provided, but it would be incorrect if it stated that FMPP is associated with infertility. While boys with FMPP may experience early puberty, their fertility is not typically affected.

**Option D:** This option is not provided, but it would be incorrect if it stated that FMPP is caused by an increase in luteinizing hormone (LH) secretion. While LH levels do increase during puberty, the underlying cause of FMPP is a genetic mutation in the androgen receptor gene, not an increase in LH.

**Clinical Pearl / High-Yield Fact**
Boys with FMPP typically exhibit accelerated bone age, which can be detected through radiographic studies. This is an important clinical finding, as it can help differentiate FMPP from other causes of precocious puberty.

**Correct Answer: D.**