Samples from fetuses (n = 13 after terminations) and newborns (n = 2) were available for targeted genomic sequencing of the exons and introns of the TSC1 and TSC2 genes and the adjacent 10 base pairs and for validated studies using Sanger sequencing.Among the 15 subjects with suspected cardiac rhabdomyoma and TSC genomic sequencing data, 7 subjects were familial and 8 subjects were sporadic cases.
In this study, we analyzed TSC1 and TSC2 in 57 Japanese patients with TSC (8 familial and 49 sporadic; 46 definite and 11 suspect TSC) and identified 31 mutations including 11 TSC1 mutations (two familial and nine sporadic; all definite TSC) and 20 TSC2 mutations (2 familial and 18 sporadic; 19 definite and 1 suspect TSC).
Data indicated that 20 mutations, including 5 mutations in TSC1 (2 sporadic, 1 familial mutation, and 2 of uncertain origin) and 15 mutations in TSC2 (14 sporadic and 1 familial mutation), 8 single-nucleotide polymorphisms (SNPs, including 3 SNPs found in irrelevant individuals without TSC phenotypes studied in the control group), and 3 variants with undetermined significance were identified, including 4 novel mutations.
Overall, significantly more TSC2 mutations were found in our population, with a relatively equal distribution of mutations between TSC1 and TSC2 among the familial cases, but a marked underrepresentation of TSC1 mutations among the sporadic cases (P = 0.0035, Fisher's exact test).