MRI scan of a mentally retarded child with recurrent seizures and hemangioma. Diagnosis is?
**Core Concept**
The question requires the identification of a rare genetic disorder that affects multiple organ systems, characterized by mental retardation, seizures, and cutaneous hemangiomas. This condition is associated with mutations in specific genes involved in cell growth and differentiation.
**Why the Correct Answer is Right**
The correct diagnosis is Sturge-Weber syndrome, a neurocutaneous disorder caused by mutations in the GNAQ gene. The GNAQ gene encodes a subunit of the G-protein complex, which plays a crucial role in signaling pathways that regulate cell growth and differentiation. The mutation leads to the formation of a port-wine stain, a type of cutaneous hemangioma, which is a hallmark of the condition. The port-wine stain is usually present on the face, scalp, or neck and is associated with seizures, mental retardation, and other neurological abnormalities. The MRI scan may show leptomeningeal angiomatosis, a characteristic feature of Sturge-Weber syndrome.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not match the clinical presentation of the patient. The patient's symptoms are more consistent with a neurocutaneous disorder, not a metabolic or infectious condition.
**Option B:** This option is incorrect because it does not account for the presence of cutaneous hemangiomas and the characteristic MRI findings of leptomeningeal angiomatosis.
**Option C:** This option is incorrect because it does not match the patient's clinical presentation. The patient's symptoms are more consistent with a neurocutaneous disorder, not a muscular dystrophy.
**Clinical Pearl / High-Yield Fact**
Sturge-Weber syndrome is a rare genetic disorder that affects multiple organ systems, and its diagnosis is often based on clinical presentation, imaging studies, and genetic testing. It is essential to recognize the characteristic port-wine stain and leptomeningeal angiomatosis on MRI scans to make an accurate diagnosis.
**Correct Answer:** C. Sturge-Weber syndrome