A 3-year-old child presents with new-onset seizures and multiple hypopigmented macules (ash-leaf spots) on the trunk. Brain imaging reveals multiple cortical tubers and a subependymal giant cell astrocytoma near the foramen of Monro. The genetic mutation responsible for this condition involves which gene?

• A TSC1 gene on chromosome 9 ✓
• B NF2 gene on chromosome 22
• C NF1 gene on chromosome 17
• D VHL gene on chromosome 3

Explanation

This child has tuberous sclerosis complex (TSC), characterized by cortical tubers, subependymal giant cell astrocytomas (SEGA), and cutaneous ash-leaf spots. TSC is caused by mutations in TSC1 (chromosome 9, encoding hamartin) or TSC2 (chromosome 16, encoding tuberin). Both are correct causative genes, but TSC1 is listed here. NF1 causes neurofibromatosis type 1. NF2 causes schwannomas and meningiomas. VHL causes von Hippel-Lindau disease with hemangioblastomas.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.