We identified an inactivating TSC1 or TSC2 variant in 83 (54%), including 65/113 (58%) of those with clinically definite TSC and 18/42 (43%) with possible TSC, or suspected of TSC but without sufficient clinical information for classification (Tables 1 and 2; and Supplementary Information Tables S4 and S5). Here, TSC2 is linked to tuberous sclerosis.