**Core Concept:** Neurocutaneous syndromes are a group of genetic disorders characterized by abnormalities of the skin, nervous system, and cranial nerves. They are caused by mutations in genes involved in neural tube development, neuronal migration, and differentiation.

**Why the Correct Answer is Right:** Tuberous sclerosis complex (TSC) is the most common neurocutaneous syndrome. It results from mutations in TSC1 or TSC2 genes, leading to dysregulation of the mTOR pathway and subsequent abnormal cell growth. The clinical manifestations include hamartomas in various organs, seizures, and intellectual disability.

**Why Each Wrong Option is Incorrect:**

A. Neurofibromatosis (NF) is a disorder characterized by the development of benign tumors in the peripheral nerves. While it is a neurocutaneous syndrome, Tuberous sclerosis complex is more common.

B. Sturge-Weber syndrome is characterized by port-wine stain on the face, seizures, and brain lesions. It is caused by a mutation in GNAQ/GNA11 genes, but less common compared to Tuberous sclerosis complex.

C. Van der Woude syndrome is characterized by cleft lip or palate and submandibular gland agenesis. Although it involves the head and neck region, it is not a neurocutaneous syndrome.

D. Proteus syndrome is characterized by abnormal growth of various tissues, including skin, bones, and brain. It is a rare condition and less common compared to Tuberous sclerosis complex.

**Clinical Pearl:** Tuberous sclerosis complex is essential to recognize as it can lead to appropriate management, surveillance, and genetic counseling for affected individuals and their families.

**Correct Answer:** Tuberous sclerosis complex (TSC) is the most common neurocutaneous syndrome. Mutation in TSC1 or TSC2 genes leads to dysregulation of the mTOR pathway and subsequent abnormal cell growth, resulting in hamartomas in various organs, including brain, seizures, and intellectual disability.