Phenotypic and genotypic characterization of Chinese children diagnosed with tuberous sclerosis complex

Clinical practice recommendations for kidney involvement in tuberous sclerosis complex: a consensus statement by the ERKNet Working Group for Autosomal Dominant Structural Kidney Disorders and the ERA Genes & Kidney Working Group

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the presence of proliferative lesions throughout the body. Management of TSC is challenging because patients have a multifaceted systemic illness with prominent neurological and developmental impact as well as potentially severe kidney, heart and lung phenotypes; however, every organ system can be involved. Adequate care for patients with TSC requires a coordinated effort involving a multidisciplinary team of clinicians and support staff. This clinical practice recommendation was developed by nephrologists, urologists, paediatric radiologists, interventional radiologists, geneticists, pathologists, and patient and family group representatives, with a focus on TSC-associated kidney manifestations. Careful monitoring of kidney function and assessment of kidney structural lesions by imaging enable early interventions that can preserve kidney function through targeted approaches. Here, we summarize the current evidence and present recommendations for the multidisciplinary management of kidney involvement in TSC.

A dermatological assessment of pediatric patients with tuberous sclerosis complex (TSC)

BACKGROUND

Tuberous sclerosis complex (TSC) is a multisystem neurocutaneous syndrome with variable phenotypes. Recent updates of TSC diagnostic criteria reaffirmed the defined genetic diagnostic criterion as the finding of a pathogenic DNA alteration in either TSC1 or TSC2 genes. It also slightly modified definite clinical diagnostic criteria. TSC-associated skin lesions in infancy are important clinical signs to select individuals with possible TSC for a closer clinical follow-up and genetic testing.

OBJECTIVE

To raise awareness of the updated TSC diagnosis criteria; to assess the frequency of skin lesions in TSC patients as well as the first dermatological presentation; and to associate the findings with either TSC1 or TSC2 mutations.

METHODS

Observational cross-sectional study. Clinical and genetic data were retrospectively collected from 37 TSC patients from a Brazilian University Hospital. Patients with skin signs were examined and prospectively assessed for 12 months.

RESULTS

The earliest cutaneous lesions were hypomelanotic macules, which together with angiofibromas were the most frequent dermatological lesions. The total pathogenic DNA alteration ratio between TSC2 and TSC1 genes was 8:1. The frequency of a TSC2 pathogenic variant was 10-fold greater in the presence of ungual fibromas.

STUDY LIMITATIONS

Small sample and a limited number of patients with TSC1 pathogenic variants.

CONCLUSION

Clinicians should be knowledgeable about TSC updated diagnostic criteria. Patients need to be followed up by a multidisciplinary team and treated accordingly. Early detection of cutaneous lesions is important for TSC diagnosis. A significant association between TSC2 gene pathogenic alterations and ungual fibromas is described.

The autism spectrum disorder phenotype in children with tuberous sclerosis complex: A systematic review and meta-analysis

AIM

To investigate the phenotype in autistic children with tuberous sclerosis complex (TSC), specifically autism spectrum disorder (ASD) severity and characteristics, intellectual ability, adaptive and executive function, language skills, attention-deficit/hyperactivity disorder features, and internalizing and externalizing behaviours.

METHOD

MEDLINE, Embase, and the Cochrane Library were searched up to March 2021. Studies that investigated predefined phenotypic factors in children with TSC-ASD were included according to the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) guidelines. Two authors independently reviewed titles, abstracts, full texts, and extracted the data. Risk of bias and GRADE assessments were completed.

RESULTS

Thirty-four studies with 3160 children with TSC, 30% with ASD, were included. Meta-analysis found that 90% (95% confidence interval 86%-94%) of children with TSC-ASD have an intellectual disability. There was some evidence to suggest that young children with TSC-ASD and idiopathic ASD have a similar pattern of severity and behaviour. Overall, data about phenotypic characteristics were limited.

INTERPRETATION

A greater proportion of children with TSC-ASD are reported to have an intellectual disability than children with idiopathic ASD. Early intervention should consider the needs of children with a high likelihood of intellectual disability. Research is needed to better understand the impacts of intellectual disability and other co-occurring difficulties on adaptive function, participation, and quality of life in TSC-ASD.

WHAT THIS PAPER ADDS

Most children with tuberous sclerosis complex (TSC) and autism spectrum disorder (ASD) have an intellectual disability. TSC-ASD early intervention planning should consider the high likelihood of intellectual disability. Quality of life and the functional impact of intellectual disability in TSC-ASD are not understood. Little is known about co-occurring difficulties in TSC-ASD.

Progress of clinical research studies on tuberous sclerosis complex-related epilepsy in China

Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous syndrome, with 75.6%-83.5% and 54.1% patients presenting with epilepsy and drug-resistant epilepsy (DRE), respectively. Clinical studies on TSC, particularly surgical interventions, have achieved rapid and substantial progress. The TSC-Task Force Committee of the China Association Against Epilepsy (CAAE-TFTSC) was founded in 2012, and annual academic conferences on the surgical treatment of TSC-related epilepsy have been held since 2013. 'China experts' consensus on surgical treatment of TSC-related epilepsy' was published in 2019. This review focuses on surgical treatment, including resective surgery, neuromodulations, corpus callosotomy and mini-invasive ablations, as well as studies on phenotype, genotype and anti-seizure therapies of mammalian target of rapamycin inhibitor, vigabatrin and ketogenic diet in patients with TSC-related DRE in China.

Genotype/phenotype correlation in 123 Chinese patients with Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC) is a multisystemic neurocutaneous disorder with autosomal dominant inheritance. We performed mutation analyses on 123 Chinese patients with "definite TSC" according to the latest diagnostic criteria. Pathogenic / likely-pathogenic variants were identified in 72.2% of all index patients (70/97), in which 35.7% (25/70) had TSC1 variants and 64.3% (45/70) had TSC2 variants. 84.5% (82/97) cases were sporadic and 15.5% (15/97) cases were familial. 62 unique variants were reported, in which 41.9% (26/62) were novel. Male patients had significantly more subependymal nodules (p=0.029) than females, whereas renal angiomyolipoma (p=0.032) occurred predominantly in females. Sporadic cases also had more renal angiomyolipoma (p=0.004), cortical tubers (p=0.008), hypopigmented macules (p=0.018) and fibrous cephalic plaques (p=0.028) than cases with known inheritance. Patients with TSC2 pathogenic variants were more likely to have mental retardation (p<0.001), cardiac rhabdomyoma (p=0.004), renal angiomyolipoma (p=0.006) and facial angiofibromas (p=0.026) than those with TSC1 pathogenic variants, while mutation-negative cases showed a mixed phenotype between those with TSC1 and TSC2 variants. There were no significant phenotypic differences between patients with and without TSC1/TSC2 variants, but TSC2 missense and in-frame variants were associated with higher frequencies of mental retardation (P<0.001), renal angiomyolipoma (p=0.001), cardiac rhabdomyoma (p=0.012) and facial angiofibroma (p=0.021) than those with TSC1 frameshift and splice site variants. Furthermore, a higher frequency of mental retardation (p=0.013) was observed in patients with TSC2 missense and in-frame variants than those with frameshift and splice site variants. All 14 antenatal-onset patients had cardiac rhabdomyoma. They had fewer seizures (p=0.028) than patients with paediatric-onset, but were more likely to have mental retardation (p=0.035) than individuals with adult-onset disease. Generally, paediatric-onset patients had more neurological manifestations, while initial presentations of adult-onset TSC were more diverse.

Sirolimus treatment for tuberous sclerosis complex prior to epilepsy: Evidence from a registry-based real-world study

OBJECTIVE

To evaluate whether sirolimus treatment could relieve the later burden of new-onset seizures in patients with tuberous sclerosis complex (TSC) prior to epilepsy.

METHODS

A real-world matched case-control study was nested in another registry cohort study. Infants with TSC (<12 months old) without seizures whose parents agreed on sirolimus treatment for other symptoms were eligible for inclusion to the early sirolimus (ES) group. These patients were enrolled from 2015 to 2018. Controls in the late sirolimus (LS) group were matched from the registry cohort database for 2015-2018. Age and genotype were used as the initial stratifying criteria and other symptoms as the greedy matching criteria at a matching ratio of 1:4. None of the preventive drugs were introduced before seizure onset or before 2 years of age in the LS group. Both groups were followed up until June 2020. The primary objective was a comparison of the characteristics of the first seizure between the two groups. The secondary objective was the assessment of the final seizure status at the endpoint.

RESULTS

There were 42 and 168 patients with TSC in the ES and LS groups, respectively. Early sirolimus treatment significantly reduced the seizure onset, especially in the patients aged <6 months. The mean onset-age was significantly delayed by sirolimus treatment (11.34±7.93 months vs. 6.94±6.03 months, P<0.001). The subtype of seizures that benefited the most was spastic (onset) seizures (all were infantile spasms) [5/42 (11.90%) vs. 73/168 (43.45%), P<0.001]; these seizures were either eliminated or alleviated. The sirolimus treatment addition prior to seizures was more effective than its addition after seizures in reducing drug-resistant epilepsy [10/42 (23.81%) vs. 70/147 (47.62%), P=0.004].

CONCLUSION

Early sirolimus treatment for TSC effectively modified the disease by preventing infantile spasms, delaying seizure onset, and relieving its severity. The anti-epileptogenic effect of sirolimus may be time- and dose-dependent.

Molecular-Genetic Characteristics and Genotype-Phenotype Correlations in Bulgarian Patients with Tuberous Sclerosis Complex

Objective

The aim of the study was to determine the molecular-genetic characteristics of the autosomal dominant systematic disorder Tuberous Sclerosis Complex (TSC1 and TSC2) in Bulgarian patients and to derive some genotype-phenotype correlations.

Material and Methods

In total 42 patients/families with suspected clinical diagnosis of TSC were analyzed. We used direct sequencing and MLPA for the TSC1 and TSC2 gene analysis.

Results

In 38 families (90.5%) we confirmed the suspected clinical diagnosis – 15 with TSC1 (35.7%) and 23 (54.8%) with TSC2. In 4 families (9.5%) pathogenic variants were not found. In all 38 patients with proven diagnosis of TSC, we found 38 different mutations, 15 of which (39%) were detected for the first time by our research group. The mutation “hotspots“ in TSC1 gene are exons 9, 15, 17 and 18, where 73% of the TSC1 mutations are localized, while the TSC2 gene mutation “hotspots“ are exons 13 and 34, with 22% of the mutations situated there. In the TSC2 patients the common clinical findings include subcortical tubers, epilepsy with generalized tonic-clonic seizures, subependymal giant cell astrocytoma, facial angiofibromas, ungual fibromas, cardiac rhabdomyomas and renal angiomyolipomas, while in the TSC1 patients typically cortical tubers, cortical dysplasia and subependymal nodules were registered. In patients with aggressive frameshift and nonsense TSC1 and TSC2 mutations commonly hypomelanotic macules, cortical and subcortical tubers, cortical dysplasia, epilepsy with different types of seizures were found. Renal angiomyolipomas and cysts were detected mainly in patients with large deletions. Shagreen patches and intellectual disability were typically registered in equal degree in patients with frameshift, nonsense and missense mutations.

Conclusion

Although some genotype-phenotype correlations were derived, there is a great inter- and intrafamilial clinical variability in TSC, so it is impossible to predict the course of the disease on the basis of the detected molecular defect. The obtained results helped us to develop a diagnostic algorithm for proper molecular-genetic diagnostics which permits adequate genetic counseling, prophylaxis and treatment in the affected TSC families.

Bronchial angiofibroma in tuberous sclerosis complex: A case report and literature review

Cutaneous angiofibroma is part of the classic triad of tuberous sclerosis complex (TSC). Angiofibroma is rarely reported to affect the mucous membranes of the trachea and bronchus. Tracheobronchial angiofibroma is also a hamartomatous manifestation of TSC. Considering the paucity of literature describing tracheal lesions in TSC, more case reports are needed to guide treatment planning. This case report adds to the existing clinical literature and provides a reference for clinical diagnosis.

Factors associated with autism spectrum disorder in children with tuberous sclerosis complex: a systematic review and meta-analysis

AIM

To investigate associations between clinical factors and the development of autism spectrum disorder (ASD) in children with tuberous sclerosis complex (TSC), specifically seizures, electroencephalogram abnormalities, tubers and other neurostructural abnormalities, and genetic factors.

METHOD

MEDLINE, Embase, PubMed, the Cochrane Library, and Web of Science were searched until January 2019. Studies that considered the predefined factors for development of ASD in children with TSC were included, following PRISMA-P guidelines. Two authors independently reviewed titles, abstracts, and full texts, extracted data, and assessed risk of bias.

RESULTS

Forty-two studies with 3542 children with TSC were included. ASD was associated with a history of seizures (odds ratio [OR] 3.79, 95% confidence interval [CI] 1.77-8.14), infantile spasms compared with other seizure types (OR 3.04, 95% CI 2.17-4.27), onset of any seizure type during infancy (OR 2.65, 95% CI 1.08-6.54), and male sex (OR 1.62, 95% CI 1.23-2.14). There was no association with tuber number, tuber location, or genotype.

INTERPRETATION

While a causal link between seizures and ASD in children with TSC cannot be inferred, a strong association between seizures and ASD in children with TSC, particularly with seizure onset during infancy and specifically infantile spasms, is present. Children with TSC and infant-onset seizures should be monitored for emerging features of ASD. What this paper adds Seizures and autism spectrum disorder (ASD) strongly associate in children with tuberous sclerosis complex (TSC). Infant-onset seizures and infantile spasms are particularly strongly associated with ASD in TSC.

A novel TSC2 c.4511 T > C missense variant associated with tuberous sclerosis complex

Background

Tuberous sclerosis complex (TSC) is an autosomal-dominant hereditary disease characterized by hamartomas of multiple organ systems, including the brain, skin, heart, kidney and lung. Genetically, TSC is caused by pathogenic variants in the TSC1 or TSC2 gene.

Case presentation

We reported a sporadic case of a 32-year-old Han Chinese male diagnosed with TSC, whose spouse had a history of two spontaneous miscarriages and an induced abortion of a 30-week fetus identified with cardiac rhabdomyoma by ultrasound. A novel heterozygous missense variant in the TSC2 gene (Exon35:c.4511 T > C:p.L1504P) was identified in the male patient and the aborted fetus by next-generation sequencing, but not in his wife or both his parents. According to the ACMG/AMP criteria, this variant was classified as a “likely pathogenic” variant.

Conclusion

The novel TSC2:c.4511 T > C variant identified was highly likely associated with TSC and could potentially lead to adverse reproductive outcomes. IVF-ET and pre-implantation genetic diagnosis for TSC are recommended for this patient in the future to prevent fetal TSC.

Mutation landscape of TSC1/TSC2 in Chinese patients with tuberous sclerosis complex

Genetic testing of TSC1 and TSC2 is important for the diagnosis of tuberous sclerosis complex (TSC), an autosomal dominant neurocutaneous disease. This study retrospectively reviewed 347 samples from patients with clinically suspected TSC being tested for mutations in TSC1 and TSC2 genes using next-generation sequencing and multiplex ligation-dependent probe amplification. Two hundred eighty-one patients (80.98%) were classified as definite/possible/uncertain diagnosis of TSC and the mutational spectrum of TSC1/TSC2 was described. Two hundred eighteen unique nonsynonymous SNVs/Indels (64 in TSC1, 154 in TSC2) and 13 copy number variants (CNVs) were identified in 241 samples (85.77%), including 82 novel variants. CNVs involving 12 large deletions and one duplication were detected exclusively in TSC2. Both TSC1 and TSC2 mutations were nearly uniformly distributed in their protein-coding regions. Furthermore, a string of non-TSC1/TSC2 deleterious variants in 12 genes was identified in the patients, especially overwhelmingly present in the patients with no mutation identified (NMI) in TSC1/TSC2. Our study provides a comprehensive TSC1/TSC2 mutation landscape and reveal some potential risk non-TSCs variants present in patients with NMI.

Mutation Spectrum of Tuberous Sclerosis Complex Patients in Indian Population

Tuberous sclerosis complex (TSC) is a multiorgan disorder characterized by formation of hamartomas and broad phenotypic spectrum including seizures, mental retardation, renal dysfunction, skin manifestations and brain tubers. It is inherited in an autosomal dominant pattern, caused due to mutation in either TSC1 or TSC2 genes. Seizures are one of the major presenting symptoms of TSC that helps in early diagnosis. The present study describes the mutation spectrum in TSC1 and TSC2 genes in TSC patients and their association with neurocognitive-behavioral phenotypes. Ninety-eight TSC patients were enrolled for TSC genetic testing after detailed clinical and neurobehavioral assessment. Large genomic rearrangement testing was performed by multiplex ligation-dependent probe amplification (MLPA) technique for all cases and Sanger sequencing was performed for MLPA negative cases. Large rearrangements were identified in approximately 1% in TSC1 and 14.3% in TSC2 genes. The present study observed the presence of duplications in two (2%) cases, both involving TSC2/PKD1 contiguous genes which to the best of our knowledge is reported for the first time. 8.1% of small variants were identified in the TSC1 gene and 85.7% in TSC2 gene, out of which 23 were novel variations and no variants were found in six (6.1%) cases. This study provides a representative picture of the distribution of variants in the TSC1 and TSC2 genes in Indian population along with the detailed assessment of neurological symptoms. This is the largest cohort study from India providing an overview of comprehensive clinical and molecular spectrum.

Autism and Epilepsy in Patients With Tuberous Sclerosis Complex

Introduction: Individuals with Tuberous Sclerosis Complex (TSC) are at increased risk of developing both epilepsy and autism spectrum disorder (ASD), but the relationship between these conditions is little understood. We reviewed published reports to elucidate the relationship between ASD, epilepsy, and TSC, and to define the genetic and neurological risk factors. Methods: Articles (January 2004-May 2019) were identified via PubMed, EMBASE, and CENTRAL databases. Article inclusion required report on individuals with TSC-associated ASD and epilepsy with prevalence, odds ratio, or rate report on the comorbidity of ASD in epileptic patients due to TSC. Results: A total of 841 abstracts were identified in the original search. Thirty-six articles were included, which identified study populations, ASD measures used, and study confounders as bias factors. This review included 2,666 TSC patients, with a mean age of 15.9 years (range 1.94-30.3 years). The percentage of TSC patients with epilepsy and autism was 33.7%. Patients with TSC and autism showed more frequent seizures and earlier epilepsy onset than TSC patients without autism. ASD and intractable epilepsy were both predicted by a higher number of areas with dysplastic features revealed in brain MR scans. ASD, the onset of seizures in children <2 years of age, and >3 tubers have all been associated with an increased risk of refractory epilepsy in TSC patients. However, the direction of the relationship is not clear because a history of epilepsy, or infantile spasms in patients with TSC is also associated with an increased likelihood of ASD. Overall, 73.2% of patients carried TSC2 genetic variant and, among patients with TSC and autism, the percentage of TSC2 individuals was 85.6%. Conclusions: The complex interrelationship between TSC, autism, and epilepsy, coupled with limited knowledge on the neurobiological basis for the interrelationship, limits overall understanding and opportunities for management. The results of this review highlight the need for early identification and management to optimize favorable outcomes in the most vulnerable individuals with TSC. Regardless of whether studies are considered individually or collectively, interpretation is made difficult due to the differences between the studies, most notably between methods and diagnostic criteria used to assess intellectual ability.

Brain Proteomic Profiling in Intractable Epilepsy Caused by TSC1 Truncating Mutations: A Small Sample Study

Tuberous sclerosis complex (TSC) is a genetic disease characterized by seizures, mental deficiency, and abnormalities of the skin, brain, kidney, heart, and lungs. TSC is inherited in an autosomal dominant manner and is caused by variations in either the TSC1 or TSC2 gene. TSC-related epilepsy (TRE) is the most prevalent and challenging clinical feature of TSC, and more than half of the patients have refractory epilepsy. In clinical practice, we found several patients of intractable epilepsy caused by TSC1 truncating mutations. To study the changes of protein expression in the brain, three cases of diseased brain tissue with TSC1 truncating mutation resected in intractable epilepsy operations and three cases of control brain tissue resected in craniocerebral trauma operations were collected to perform protein spectrum detection, and then the data-independent acquisition (DIA) workflow was used to analyze differentially expressed proteins. As a result, there were 55 up- and 55 down-regulated proteins found in the damaged brain tissue with TSC1 mutation compared to the control. Further bioinformatics analysis revealed that the differentially expressed proteins were mainly concentrated in the synaptic membrane between the patients with TSC and the control. Additionally, TSC1 truncating mutations may affect the pathway of amino acid metabolism. Our study provides a new idea to explore the brain damage mechanism caused by TSC1 mutations.

Genotype and Phenotype Analysis of Chinese Children With Tuberous Sclerosis Complex: A Pediatric Cohort Study

Tuberous sclerosis complex (TSC) is a genetic condition characterized by the occurrence of hamartomatous wounds stemming from the dysfunction of the mammalian target of rapamycin (mTOR) pathway. We investigated the clinical phenotypes and genetic variants in 243 unrelated probands and their families in China. Exome sequencing, targeted sequencing or multiplex ligation-dependent probe amplification (MLPA) was performed in 174 children with TSC, among whom 31 (17.82%) patients/families were identified as having pathogenic or likely pathogenic variants in the TSC1 gene, 120 (68.97%) as having pathogenic or likely pathogenic variants in the TSC2 gene and 23 (13.21%) as having no pathogenic or likely pathogenic variants identified (NMI). In the 31 patients with pathogenic or likely pathogenic TSC1 variants, 10 novel variants were detected among 26 different variants. In all 120 patients with TSC2 variants, 39 novel variants were found among a total of 107 different variants. We compared the phenotypes of the individuals with TSC1 pathogenic variants, TSC2 pathogenic variants and NMI. Patients with TSC2 variants were first diagnosed at a younger age (p = 0.003) and had more retinal hamartomas (p = 0.003) and facial angiofibromas (p = 0.027) (age ≥ 3 years) than individuals with TSC1 variants. Compared with individuals with TSC1/TSC2 pathogenic variants, NMI individuals had fewer cortical tubers (p = 0.003). Compared with individuals with TSC1 pathogenic variants, NMI patients had more retinal hamartomas (p = 0.035), and compared with individuals with TSC2 pathogenic variants, they had less epilepsy (p = 0.003) and fewer subependymal nodules (SENs) (p = 0.004).

Mutational analysis of renal angiomyolipoma associated with tuberous sclerosis complex and the outcome of short-term everolimus therapy

To identify clinical characteristics and mutation spectra in Chinese patients with renal angiomyolipoma (AML) associated with the tuberous sclerosis complex (TSC, TSC-AML), examined the efficacy and safety of short-term everolimus therapy (12 weeks). We analyzed the frequency distribution of each TSC-related clinical feature and investigated gene mutations by genetic testing. Some subjects received everolimus for 12 weeks at a dose of 10 mg/day, and the efficacy and safety of short-term everolimus therapy were examined. Finally, 82 TSC-AML patients were enrolled for analysis in this study. Of the 47 patients who underwent genetic testing, 22 patients (46.81%) had at least one detectable mutation in the TSC1 or TSC2 gene: 7 were TSC1 gene mutations, 13 were TSC2 gene mutations, and 2 were found in both TSC1 and TSC2. Everolimus treatment had a statistically significant effect on the renal AML volume reduction during follow-up (P < 0.05), and the mean reduction rate of volume for all cases was 56.47 ± 23.32% over 12 weeks. However, 7 patients (7/25; 28.00%) experienced an increase in renal AML tumor volume within 12 weeks after discontinuation of the everolimus treatment. Although most patients (27/30, 90.00%) experienced some adverse events during the treatment period, all such events were mild, and no patients discontinued or needed dose reduction because of adverse events. Overall, in this study, the mutation rate of TSC-AML patients is much lower than other reports. Short-term everolimus treatment for TSC-AML is effective and safe, but the stability is much lower than long-term therapy.

Genetic Evaluation of Common Neurocutaneous Syndromes

The neurocutaneous syndromes are a group of multisystem disorders that affect the skin and central nervous system. Neurofibromatosis 1, neurofibromatosis 2, tuberous sclerosis complex, and Sturge-Weber syndrome are the four major neurocutaneous disorders that mainly present in childhood. In this review, we discuss the clinical findings and genetic diagnosis, related genes/pathways and genotype-phenotype correlations of these four neurocutaneous syndromes.

Genetics, genomics, and genotype-phenotype correlations of TSC: Insights for clinical practice

Tuberous Sclerosis Complex (TSC) is a multisystem autosomal dominant condition caused by inactivating pathogenic variants in either the TSC1 or the TSC2 gene, leading to hyperactivation of the mTOR pathway. Here, we present an update on the genetic and genomic aspects of TSC, with a focus on clinical and laboratory practice. We briefly summarize the structure of TSC1 and TSC2 as well as their protein products, and discuss current diagnostic testing, addressing mosaicism. We consider genotype-phenotype correlations as an example of precision medicine, and discuss genetic counseling in TSC, with the aim of providing geneticists and health care practitioners involved in the care of TSC individuals with useful tools for their practice.

A novel TSC2 missense variant associated with a variable phenotype of tuberous sclerosis complex: case report of a Chinese family

Background

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder characterized by the development of hamartomas in multiple organs, including the brain, heart, skin, kidney, lung and retina. A diagnosis of TSC is established with a recently revised clinical/radiological set of criteria and/or a causative mutation in TSC1 or TSC2 gene.

Case presentation

We report a Chinese TSC family with two siblings presenting with multiple hypomelanotic macules, cardiac rhabdomyomas and cortical tubers associated with a small subependymal nodule. The older child had seizures. A novel heterozygous missense variant in the TSC2 gene (c.899G > T, p.G300 V) was identified and shown to be inherited from their father as well as paternal grandfather, both of whom presented with variable TSC-associated signs and symptoms.

Conclusion

We identified a novel heterozygous TSC2 variant c.899G > T as the causative mutation in a Chinese family with TSC, resulting in wide intrafamilial phenotypic variability. Our study illustrates the importance of clinical evaluation and genetic testing for family members of the patient affected with TSC.

First five generations Chinese family of tuberous scleroses complex due to a new mutation of the TSC1 gene

Tuberous scleroses complex (TSC) is a rare neurocutaneous syndrome and has autosomal dominant inheritance. However, larger family with TSC is very rare. Here, we report the first five generations family with TSC from China, and localize the pathogenic gene. A boy with TSC and epilepsy underwent preoperative evaluation and epileptic surgery. His TSC family history was gotten, and the clinical data of a Chinese family with TSC were collected in 2016. Complete exons sequencing was performed in the proband and his parents, and whole exons sequence of TSC was performed in the other family members. The family showed autosomal dominant inheritance, and it was the largest reported family with TSC. In this pedigree, there were 14 patients in 5 generations, but only 1 case with epilepsy in them. All of examined patients had TSC 1 gene exon 15 c.1846delG p.A616Pfs^*13 mutation. In conclusion, TSC patients with TSC 1 deletion presented mild neurological symptom and rendered larger family.

Novel mutations in Chinese Han patients with tuberous sclerosis complex: Case series and review of the published work

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease characterized by hamartomas in multiple organ systems. This study was performed in one familial and two sporadic cases with TSC. Two novel mutations (c.1884_1887delAAAG and c.5266A>G) and two previously reported mutations (c.4258_4261delTCAG and c.1960G>C) were identified by direct DNA sequencing. Of the four mutations, c.1884_1887delAAAG and c.1960G>C were found in a family and identified in the same allele by TA cloning sequencing. However, c.1960G>C was reported to be non-pathogenic. Furthermore, correlations between genotypes and phenotypes of Chinese Han patients since 2014 were performed by paired χ² -tests in our published work review, which has not been reported. The results showed that patients with TSC2 mutations had a higher frequency of mental retardation and there were no significant differences of seizures and skin lesions with TSC1 mutations. Genetically, they had a higher frequency of familial inheritance.

Pattern of TSC1 and TSC2 germline mutations in Russian patients with tuberous sclerosis

Tuberous sclerosis (TS) is a rare autosomal-dominant genetic disease. TS is manifested by the development of multiple hamartomas, which affect brain, kidneys, retina, skin and other organs. This study aimed to reveal specific features of molecular epidemiology of TS in Russia. Blood DNA samples from 61 patients with definite (n = 53) or probable (n = 8) clinical diagnosis of TS were tested for mutations in TSC1 and TSC2 genes using Sanger sequencing and MLPA analysis. Five TSC1/2 mutation-negative patients were further analyzed by exome sequencing. TSC1/2 mutations were detected in 53/61 patients (87%): 39 (74%) carried mutations in the TSC2 and 14 (26%) in the TSC1. Large rearrangements (exon deletions/duplications) affected exclusively TSC2, accounting for 15% of lesions of this gene. 6/8 (75%) patients with incomplete clinical manifestation of TS carried TSC1/2 gene lesion. Overall, 96% of detected germline TSC1/2 mutations occurred de novo. Patients with no mutation identified (NMI) differed from TSC1/2 mutation carriers, being lacking cortical tubers and subependymal nodules but having higher frequencies of renal angiomyolipomas, rhabdomyomas, and lymphangioleiomyomatosis. Exome sequencing failed to identify overt disease-causing mutation candidates among NMI patients. Russian patients with TS have increased frequency of TSC2 large gene rearrangements and TSC1/2 mutations occurring de novo as compared to other studies. Patients with suspected TS diagnosis but NMI status may represent a distinct disease entity.