Analysis of bothTSC1 andTSC2 for germline mutations in 126 unrelated patients with tuberous sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in the TSC1 and TSC2 genes on chromosomes 9 and 16 respectively. Diagnosis is based on clinical features but can be difficult as a result of variable phenotypic expression. With the advantage of mutation analysis in making a diagnosis of TSC, and improved identification of the associated clinical features, there have been few new data on its prevalence and on the proportion of cases due to new mutations. We have performed a retrospective epidemiological study on the prevalence of TSC, the clinical features attributed to it, and the availability of mutational analysis. We identified 73 known patients with TSC (5 deceased): 39 were female and 34 male. Ages ranged from 10 months to 69 years, with a mean age of 27 years 11 months (SD 16y 10mo). The point prevalence of TSC in our study was estimated at 1 out of 24 956 on the prevalence day (30 April 2004). The majority of patients (42.5%) were diagnosed at less than 15 months of age; 25% were not given a diagnosis on first developing symptoms. In all, 93.2% had epilepsy and 71.2% had a learning disability.* A mutation was identified in 95.8% of those tested (26% TSC1 and 74% TSC2). TSC2 mutations were correlated with a more severe phenotype. The new mutation rate was calculated at 64%. We conclude that the prevalence of TSC is higher than previously calculated. We recommend that all children with epilepsy be assessed for features of TSC. Larger studies will be required to assess the prevalence of mutations in each gene, and genotype-phenotype correlation.

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“…Similar results have been seen previously (80% of cases 17 ), of which 21.6% were TSC1 and 78.4% TSC2.…”

Section: New Mutation Ratesupporting

confidence: 92%

Tuberous sclerosis complex: clinical features, diagnosis, and prevalence within Northern Ireland

Devlin¹,

Shepherd²,

Crawford³

et al. 2007

Developmental Medicine &Amp; Child Neurology

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“…HD and SSCP detect only two and five single base substitutions, respectively. Previous data from our group showed a nearly 60% of mutation detecting ability for screening the mutation unknown patient populations of tuberous sclerosis complex (TSC) using the same methods [77,78]. It seems that the present study included relatively large size PCR products which reduced SSCP/HA sensitivity.…”

Section: Discussionmentioning

confidence: 95%

Development of a simple and highly sensitive mutation screening system by enzyme mismatch cleavage with optimized conditions for standard laboratories

Tsuji

Niida

2008

Electrophoresis

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Efficient screening of unknown DNA variations is one of the substantive matters of molecular biology even today. Historically, single-strand conformation polymorphism (SSCP) and heteroduplex analysis (HA) are the most commonly used methods for detecting DNA variations everywhere in the world because of their simplicity. However, the sensitivity of these methods is not satisfactory for screening purpose. Recently, several new PCR based mutation screening methods have been developed, but most of them require special instruments and adjustment of conditions for each DNA sequence to attain the maximum sensitivity, eventually becoming as inconvenient as old methods. Enzyme mismatch cleavage (EMC) is potentially an ideal screening method. With high performance nucleases and once experimental conditions are optimized, it requires only conventional staff and conditions remain the same for each PCR product. In this study we tested four commercially available endonucleases for EMC and optimized the electrophoresis and developing conditions. We prepared 25 known DNA variations consisting of 18 single base substitutions (8 transitions and 10 transversions, including all possible sets of mismatches) and 7 small deletions or insertions. The combination of CEL nuclease, 12% polyacrylamide gel electrophoresis and rapid silver staining can detect all types of mutations and achieved 100% sensitivity.

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“…Therefore, there was strong disagreement between the functional assessment and the LOVD classification for only three TSC2 variants, K599M, R951S, and L1773I. The TSC2 K599M substitution is classified as pathogenic in the TSC2 LOVD because it was reported to be a de novo change [Niida et al, 1999] that reduced the TSC2-dependent inhibition of 4E-BP1 phosphorylation in vitro [Tee et al, 2002]. However, consistent with our previous studies [Nellist et al, 2001, in our assay, the K599M substitution did not affect TSC1 or TSC2 stability and inhibited S6K T389 phosphorylation as effectively as wild-type TSC2.…”

Section: Discussionmentioning

confidence: 99%

“…Most individuals with TSC have epilepsy and many suffer from cognitive impairments and/or autism-spectrum disorders. Mutations in either the TSC1 gene on chromosome 9q34 (MIM] 605284) [van Slegtenhorst et al, 1997], or the TSC2 gene on chromosome 16p13.3 (MIM] 191092) [European Chromosome 16 Tuberous Sclerosis Consortium, 1993] cause TSC and comprehensive mutation screens in TSC patients have identified a wide variety of pathogenic mutations [Au et al, 2007;Dabora et al, 2001;Jones et al, 1999;Niida et al, 1999;Sancak et al, 2005]. Most TSC1 and TSC2 mutations result in premature termination of the respective open-reading frame and complete inactivation of the mutated allele.…”

Section: Introductionmentioning

confidence: 99%

Functional assessment of variants in the TSC1 and TSC2 genes identified in individuals with Tuberous Sclerosis Complex

et al. 2011

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The effects of missense changes and small inframe deletions and insertions on protein function are not easy to predict, and the identification of such variants in individuals at risk of a genetic disease can complicate genetic counselling. One option is to perform functional tests to assess whether the variants affect protein function. We have used this strategy to characterize variants identified in the TSC1 and TSC2 genes in individuals with, or suspected of having, Tuberous Sclerosis Complex (TSC). Here we present an overview of our functional studies on 45 TSC1 and 107 TSC2 variants. Using a standardized protocol we classified 16 TSC1 variants and 70 TSC2 variants as pathogenic. In addition we identified eight putative splice site mutations (five TSC1 and three TSC2). The remaining 24 TSC1 and 34 TSC2 variants were classified as probably neutral.

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Analysis of bothTSC1 andTSC2 for germline mutations in 126 unrelated patients with tuberous sclerosis

Cited by 142 publications

References 42 publications

Tuberous sclerosis complex: clinical features, diagnosis, and prevalence within Northern Ireland

Tuberous sclerosis complex: clinical features, diagnosis, and prevalence within Northern Ireland

Development of a simple and highly sensitive mutation screening system by enzyme mismatch cleavage with optimized conditions for standard laboratories

Functional assessment of variants in the TSC1 and TSC2 genes identified in individuals with Tuberous Sclerosis Complex

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