Histologically confirmed WHO grade I SEGA; immunoreactive for GFAP and S-100; whole chromosome losses of 3, 6, 10, 11, 13, 14, 17, 18, 21, and X; variants inTP53,NF1, andPTENgenes; further genetic analysis for tuberous sclerosis pending. The gene discussed is GFAP; the disease is tuberous sclerosis.