**Core Concept**
Sturge Weber syndrome is a rare, congenital disorder characterized by a port-wine stain (nevis flammeus) on the face, typically involving the ophthalmic division of the trigeminal nerve, and associated with leptomeningeal angiomatosis, seizures, and intellectual disability. This condition results from a somatic mutation in the GNAQ gene, leading to abnormal vascular development.

**Why the Correct Answer is Right**
The port-wine stain in Sturge Weber syndrome is a result of the abnormal development of blood vessels in the skin and brain, which is due to the mutation in the GNAQ gene. This gene encodes for a subunit of the G-protein coupled receptor, which plays a crucial role in signal transduction pathways involved in vascular development. The leptomeningeal angiomatosis associated with this condition leads to seizures and intellectual disability due to the compression of brain tissue and the disruption of normal brain function. The seizures in Sturge Weber syndrome are often intractable and can be a major management challenge.

**Why Each Wrong Option is Incorrect**
**Option B:** Tuberous sclerosis is a genetic disorder characterized by the growth of non-cancerous tumors in various organs, including the brain, but it is not typically associated with a port-wine stain or leptomeningeal angiomatosis.
**Option C:** Von-Hippel-Lindau disease is a rare genetic disorder that predisposes individuals to develop benign and malignant tumors in various organs, including the central nervous system, but it is not associated with a port-wine stain or seizures.
**Option D:** Von Recklinghausen's disease, also known as neurofibromatosis type 1, is a genetic disorder characterized by the growth of non-cancerous tumors in the nervous system, but it is not typically associated with a port-wine stain or leptomeningeal angiomatosis.

**Clinical Pearl / High-Yield Fact**
Sturge Weber syndrome is often associated with a characteristic "tram-track" calcification on computed tomography (CT) scans of the brain, which is a result of the calcification of the leptomeningeal angiomatosis. This finding is a key diagnostic clue for this condition.

**✓ Correct Answer: A. Sturge Weber syndrome**