TSC1 and tuberous sclerosis: Even monozygotic twins with the same mutation can exhibit different clinical expressions.[6] The atypical clinical presentation indicates the potential shortcomings of the current diagnostic criteria for TSC.[7] A pathogenic variant of either TSC1 or TSC2 detected by genetic analysis represents a separate diagnostic criterion, regardless of clinical findings.[8] With advances in genomic DNA sequencing technology, it is now easy to analyze the entire sequence of TSC genes.