Mutational analysis in a cohort of 224 tuberous sclerosis patients indicates increased severity of TSC2, compared with TSC1, disease in multiple organs.
By S. Dabora, S. Jóźwiak, D. Franz, P. Roberts, A. Nieto, Joon Chung, Y. Choy, M. Reeve, E. Thiele, J. Egelhoff and 3 more. American Journal of Human Genetics, 2001
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Tuberous sclerosis (TSC) is a relatively common hamartoma syndrome caused by mutations in either of two genes, TSC1 and TSC2. Here we report comprehensive mutation analysis in 224 index patients with TSC and correlate mutation findings with clinical features. Denaturing high-performance liquid chromatography, long-range polymerase chain reaction (PCR), and quantitative PCR were used for mutation detection. Mutations were identified in 186 (83%) of 224 of cases, comprising 138 small TSC2 mutations, 20 large TSC2 mutations, and 28 small TSC1 mutations. A standardized clinical assessment instrument covering 16 TSC manifestations was used. Sporadic patients with TSC1 mutations had, on average, milder disease in comparison with patients with TSC2 mutations, despite being of similar age. They had a lower frequency of seizures and moderate-to-severe mental retardation, fewer subependymal nodules and cortical tubers, less-severe kidney involvement, no retinal hamartomas, and less-severe facial angiofibroma. Patients in whom no mutation was found also had disease that was milder, on average, than that in patients with TSC2 mutations and was somewhat distinct from patients with TSC1 mutations. Although there was overlap in the spectrum of many clinical features of patients with TSC1 versus TSC2 mutations, some features (grade 2-4 kidney cysts or angiomyolipomas, forehead plaques, retinal hamartomas, and liver angiomyolipomas) were very rare or not seen at all in TSC1 patients. Thus both germline and somatic mutations appear to be less common in TSC1 than in TSC2. The reduced severity of disease in patients without defined mutations suggests that many of these patients are mosaic for a TSC2 mutation and/or have TSC because of mutations in an as-yet-unidentified locus with a relatively mild clinical phenotype.
Subfields: Oncology, Physiology
View Paper: https://www.semanticscholar.org/paper/e98ee72581b7b2fcf02baed68904d76292a53c06
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Citations in the corpus
- The natural history of epilepsy in tuberous sclerosis complex (2009, neutral): “Previous work evaluating genotype–phenotype relationships in patients with TSC1 and TSC2 have similarly found that patients with TSC2 mutations experience higher frequency of seizures than those with TSC1 mutations (Dabora et al., 2001; Jansen et al., 2008a).”
- TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling (2002, background): “Many mutations in TSC1 and TSC2 have previously been identified in patient”
- A mouse model of TSC1 reveals sex-dependent lethality from liver hemangiomas, and up-regulation of p70S6 kinase activity in Tsc1 null cells. (2002, background): “Both rat and mouse models of TSC2 disease have been identified or generated (23–27).”
- Tuberous Sclerosis Complex Diagnostic Criteria Update: Recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference (2013, background): “Shagreen patches are observed in about 50% of individuals with TSC and typically have their onset in the first decade of life.(15,16,18,21)”