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

Multi-dimensional Insight into the Coexistence of Pathogenic Genes for ADAR1 and TSC2: Careful Consideration is Essential for Interpretation of ADAR1 Variants

Aicardi-Goutières syndrome 6 (AGS6) is a serious auto-immunization-associated acute neurologic decompensation. AGS6 manifests as acute onset of severe generalized dystonia of limbs and developmental regression secondary to febrile illness mostly. Dyschromatosis symmetrica hereditaria (DSH), as pigmentary genodermatosis, is a characterized mixture of hyperpigmented and hypopigmented macules. Both AGS6 and DSH are associated with ADAR1 pathogenic variants. To explore the etiology of a proband with developmental regression with mixture of hyperpigmentation and hypopigmentation macules, we used the trio-WES. Later, to clarify the association between variants and diseases, we used guidelines of ACMG for variants interpretation and quantitative Real-time PCR for verifying elevated expression levels of interferon-stimulated genes, separately. By WES, we detected 2 variants in ADAR1 and a variant in TSC2, respectively, were NM_001111.5:c.1096_1097del, NM_001111.5:c.518A>G, and NM_000548.5:c.1864C>T. Variants interpretation suggested that these 3 variants were both pathogenic. Expression levels of interferon-stimulated genes also elevated as expected. We verified the co-occurrence of pathogenic variants of ADAR1 and TSC2 in AGS6 patients with DSH. Our works contributed to the elucidation of ADAR1 pathogenic mechanism, given the specific pathogenic mechanism of ADAR1, and it is necessary to consider with caution when variants were found in ADAR1.

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.

Telemedicine during the COVID-19 epidemic improves outcomes in children with tuberous sclerosis complex: A 1206 visits retrospective cohort study

AIMS

To evaluate the benefits of telemedicine in children with tuberous sclerosis complex during the COVID-19 pandemic.

METHODS

A retrospective cohort study was conducted, comparing telemedicine and in-person visits within the timeframe spanning from June 1, 2021, to June 1, 2022. Disparities in demographics, emergency visits, hospitalizations, adverse effects (AEs) associated with sirolimus, and the incidence of drug-refractory epilepsy (DRE) between telehealth and in-person care were assessed. Additionally, distinctions between audio and video telehealth, as well as varying frequencies of telehealth encounters, were investigated and reported as odds ratios (ORs).

RESULTS

A total of 378 patients with 1206 visits were included, of which 137 were telemedicine patients and 241 were in-person patients. The median age was 5.0 years (IQR 2.8-10.0 years). There were 197 males (52.12%), 691 in-person visits (57.30%), and 515 telemedicine visits (42.70%). Children under 12 years old, those farther away from the center, mothers with more than 12 years of education, and children treated with sirolimus were more likely to visit via telemedicine. Telehealth was associated with significantly fewer emergency visits, hospitalizations, AEs of sirolimus, and DRE. With 10 or more visits, the incidence of emergency visits, hospitalization, and DRE was significantly reduced.

CONCLUSION

Telemedicine visits are almost as close in number as in-person visits. Younger patients, patients in remote areas, and mothers with higher education levels are more willing to complete telemedicine visits. Telemedicine visits were associated with a significantly lower number of emergency visits, hospitalizations, and AEs of sirolimus. Patients with more than 10 visits per year seemed to have better clinical outcomes.

The Genetics of Tuberous Sclerosis Complex and Related mTORopathies: Current Understanding and Future Directions

The mechanistic target of rapamycin (mTOR) pathway serves as a master regulator of cell growth, proliferation, and survival. Upregulation of the mTOR pathway has been shown to cause malformations of cortical development, medically refractory epilepsies, and neurodevelopmental disorders, collectively described as mTORopathies. Tuberous sclerosis complex (TSC) serves as the prototypical mTORopathy. Characterized by the development of benign tumors in multiple organs, pathogenic variants in TSC1 or TSC2 disrupt the TSC protein complex, a negative regulator of the mTOR pathway. Variants in critical domains of the TSC complex, especially in the catalytic TSC2 subunit, correlate with increased disease severity. Variants in less crucial exons and non-coding regions, as well as those undetectable with conventional testing, may lead to milder phenotypes. Despite the assumption of complete penetrance, expressivity varies within families, and certain variants delay disease onset with milder neurological effects. Understanding these genotype-phenotype correlations is crucial for effective clinical management. Notably, 15% of patients have no mutation identified by conventional genetic testing, with the majority of cases postulated to be caused by somatic TSC1/TSC2 variants which present complex diagnostic challenges. Advancements in genetic testing, prenatal screening, and precision medicine hold promise for changing the diagnostic and treatment paradigm for TSC and related mTORopathies. Herein, we explore the genetic and molecular mechanisms of TSC and other mTORopathies, emphasizing contemporary genetic methods in understanding and diagnosing the condition.

Specific Features of Focal Cortical Dysplasia in Tuberous Sclerosis Complex

Patients with tuberous sclerosis complex present with cognitive, behavioral, and psychiatric impairments, such as intellectual disabilities, autism spectrum disorders, and drug-resistant epilepsy. It has been shown that these disorders are associated with the presence of cortical tubers. Tuberous sclerosis complex results from inactivating mutations in the TSC1 or TSC2 genes, resulting in hyperactivation of the mTOR signaling pathway, which regulates cell growth, proliferation, survival, and autophagy. TSC1 and TSC2 are classified as tumor suppressor genes and function according to Knudson's two-hit hypothesis, which requires both alleles to be damaged for tumor formation. However, a second-hit mutation is a rare event in cortical tubers. This suggests that the molecular mechanism of cortical tuber formation may be more complicated and requires further research. This review highlights the issues of molecular genetics and genotype-phenotype correlations, considers histopathological characteristics and the mechanism of morphogenesis of cortical tubers, and also presents data on the relationship between these formations and the development of neurological manifestations, as well as treatment options.

Prenatal diagnosis and intervention improve developmental outcomes and epilepsy prognosis in children with tuberous sclerosis complex

AIM

To assess whether prenatal diagnosis and early intervention are beneficial for developmental outcomes and epilepsy prognosis in individuals with tuberous sclerosis complex (TSC).

METHOD

This retrospective study originated from a single-centre TSC-specific cohort. We enrolled 273 individuals (138 males, 145 females; 2 years-7 years 6 months, mean 4 years 5 months, SD 1 year 6 months) with definitive TSC who completed TSC1/TSC2 genetic testing and were followed up to 2 years of age. The benefits of early attention and intervention were assessed by comparing epilepsy and developmental outcomes between groups with or without a prenatal diagnosis and with or without presymptomatic preventive intervention.

RESULTS

The epilepsy occurrence rate was significantly lower in individuals diagnosed prenatally than in individuals diagnosed postnatally (p = 0.027). In individuals diagnosed prenatally, the epilepsy rate in the preventive intervention subgroup was significantly lower than that in the subgroup without preventive intervention (p = 0.008). Significant improvements in cognitive, language, and motor development were observed in individuals diagnosed prenatally compared to individuals diagnosed postnatally and in the preventive intervention subgroup compared to the subgroup without preventive intervention (p < 0.05).

INTERPRETATION

Based on this study, we cautiously speculate that early postpartum intervention may reduce the incidence of epilepsy and intractable epilepsy and improve developmental outcomes. Prophylactic intervention with sirolimus and vigabatrin may reduce the incidence of epilepsy. Larger prospective randomized controlled studies are required to support these findings.

WHAT THIS PAPER ADDS

Prenatal diagnosis and early intervention may improve developmental outcomes in children with tuberous sclerosis complex (TSC). Prophylactic intervention with sirolimus and vigabatrin may reduce the incidence of epilepsy. Cardiac and/or intracranial lesions combined with genetic testing can be used to diagnose TSC prenatally.

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.

Noninvasive prenatal diagnosis based on cell-free DNA for tuberous sclerosis: A pilot study

BACKGROUND

Noninvasive prenatal diagnosis (NIPD) based on cell-free DNA (cfDNA) has been introduced into the clinical application for some monogenic disorders but not for tuberous sclerosis (TSC) yet, which is an autosomal dominant disease caused by various variations in TSC1 or TSC2 gene. We aimed to explore the feasibility of NIPD on TSC.

METHODS

We recruited singleton pregnancies at risk of TSC from 14 families with a proband child. Definitive NIPD for TSC was performed using targeted next-generation sequencing of cfDNA in parallel with maternal white blood cell DNA (wbcDNA). The NIPD results were validated by amniocentesis or postnatal gene testing and follow-up of the born children.

RESULTS

Missense mutations, nonsense mutations, frameshift mutations, and splice-site variants which were obtained through de-novo, maternal, or paternal inheritance were included. The mean and minimum gestational weeks of NIPD were 17.18 ± 5.83 and 8 weeks, respectively. The NIPD results were 100% consistent with the amniocentesis or postnatal gene testing and follow-up of the born children.

CONCLUSION

This study demonstrates that NIPD based on cfDNA is feasible for TSC, but required to be confirmed with more samples. Studies on TSC can contribute to the application and promotion of NIPD for monogenic disorders.

Reviewing the occurrence of large genomic rearrangements in patients with inherited cancer predisposing syndromes: importance of a comprehensive molecular diagnosis

INTRODUCTION

Hereditary cancer predisposition syndromes are caused by germline pathogenic or likely pathogenic variants in cancer predisposition genes (CPG). The majority of pathogenic variants in CPGs are point mutations, but large gene rearrangements (LGRs) are present in several CPGs. LGRs can be much more difficult to characterize and perhaps they may have been neglected in molecular diagnoses.

AREAS COVERED

We aimed to evaluate the frequencies of germline LGRs in studies conducted in different populations worldwide through a qualitative systematic review based on an online literature research in PubMed. Two reviewers independently extracted data from published studies between 2009 and 2020. In total, 126 studies from 37 countries and 5 continents were included in the analysis. The number of studies in different continents ranged from 3 to 48 and for several countries there was an absolute lack of information. Asia and Europe represented most of the studies, and LGR frequencies varied from 3.04 to 15.06% in different continents. MLPA was one of the methods of choice in most studies (93%).

EXPERT OPINION

The LGR frequencies found in this review reinforce the need for comprehensive molecular testing regardless of the population of origin and should be considered by genetic counseling providers.

Identification of TSC2 mosaic mutation limited to cortical tuber with TSC targeted sequencing: a case report and literature review

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder, mainly in childhood presents epilepsy due to cortical tubers. TSC1/TSC2 pathogenic variants cannot be detected in regular molecular genetic testing in around 10-15% of TSC patients.

METHODS

We analyzed TSC genes in both cortical tuber, blood and skin samples from a pediatric patient with refractory epilepsy.

RESULTS

We found no germline mutations by whole-exome sequencing. Well in targeted sequencing of TSC1/2 data, we identified de novo mutations only in cortical tuber: TSC2 NM_000548.5: exon34:c.4183C>T (p.Gln1395*) in 3% of the alleles. No other TSC mutations were found in patient's blood and skin samples and her parents' blood sample.

CONCLUSION

Our case report found TSC2 mosaic mutations can be only limited to cortical tuber in patients with TSC.

A multistep approach to the genotype-phenotype analysis of Polish patients with tuberous sclerosis complex

The aim of this study was to evaluate a cost-effective diagnostic strategy for identification of casual variants for tuberous sclerosis complex (TSC) in the Polish population and to correlate the genetic results with selected phenotypic features. Fifty-five patients, aged 3-44 years, with a clinical diagnosis of TSC were enrolled into the study. All patients received a three-step analysis: next generation sequencing screening (NGS), multiplex ligation-dependent probe amplification (MLPA) and deep sequencing. This multistep approach obtained positive results in 51/55 (93%) patients: of the 51 positives TSC1 variants were observed in 16 (31%) and TSC2 variants in 35 (69%); these included 13 novel variants and two patients with mosaicism. Four patients (7%) had no mutation identified (NMI). Among the TSC1 gene variants, there were five nonsense, four frameshift, three large deletions, two missense and two splicing variants. For the TSC2 gene, 11 were missense, eight splicing, six frameshift, four large deletions, two in-frame deletions and four nonsense variants. The patients with TSC2 changes had their clinical diagnosis of TSC at a younger age than those with TSC1 changes (one year vs three years, p = 0.041). The TSC2 group demonstrated a higher number of major symptoms per patient (p = 0.04). Subependymal giant cell astrocytoma with concomitance of other brain lesions was more common in patients with missense mutations in either gene (23% vs 0%, p = 0.02). Such a multistep molecular diagnostic strategy could increase the possibility of detecting causal variants for TSC and may allow detection of mosaicism at low levels. Missense pathogenic variants in TSC1 or TSC2 gene might be associated with a higher risk of brain lesions.

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.

Correlation between epilepsy and genotype: A large retrospective tuberous sclerosis complex cohort

OBJECTIVE

To describe the first large population (n = 297) with tuberous sclerosis complex (TSC) in China and to examine the relationship between variants (type and location) and epilepsy.

METHODS

All exons and intron-exon boundaries of TSC1/TSC2 were sequenced with next-generation sequencing, and the distribution of several variants and associations between variant types and epilepsy were investigated.

RESULTS

Epilepsy occurred in 83.5% (248/297) of the individuals. The TSC1/TSC2 gene variant detection rate was 89.6% (266/297). The rate of epilepsy was significantly higher in the TSC2 group than in the TSC1 (p = 0.02) and no mutation identified (NMI) groups (p = 0.0005). TSC2 individuals are more likely to have spasms than TSC1 individuals (p =0.03). The age at epilepsy onset of individuals in the TSC2 group was younger than that of individuals in the TSC1 group (p = 0.008) and NMI group (p = 0.01). The age at epilepsy onset with truncated variants in the TSC1 group was significantly younger than that of individuals with nontruncated variants (p = 0.0001). The rate of epilepsy was significantly higher if variants occurred in the functional domain than in the nonfunctional domain in TSC2 individuals (p = 0.02).

CONCLUSION

This was the first large cohort study of the Chinese TSC population in which a comparative analysis of genotype and epilepsy was conducted. Individuals with TSC2 variants appeared to have more severe epileptic phenotypes, such as younger age at epilepsy onset, than those with TSC1 variants and NMI, and individuals with variants that occurred in TSC2 functional domains were more prone to epilepsy and had a younger age at epilepsy onset.

Assessment of tuberous sclerosis-associated neuropsychiatric disorders using the MINI-KID tool: a pediatric case-control study

Background

The tuberous sclerosis-associated neuropsychiatric disorders (TAND) have not previously been studied in China. We aimed to assess the psychiatric level of individuals with TAND using the Mini International Neuropsychiatric Interview for Children (MINI-KID) in China.

Results

A total of 83.16% of individuals (79/95) had at least one TAND, and 70.53% (67/95) had an intellectual disability. The MINI-KID tool diagnosed 16 neuropsychiatric diseases, the most common of which were attention-deficit/hyperactivity disorder (ADHD) (51.58%, 49/95) and social anxiety disorder (30.53%, 29/95). The number of children with psychiatric diseases in the tuberous sclerosis complex (TSC) group was significantly greater than the number in the typically developing group (P < 0.0001). Notably, 69.47% (66/95) had two or more psychiatric disorders. Pervasive developmental disorder (PDD) was often co-morbid with other psychiatric disorders.

Conclusions

This study used the structured and systematic MINI-KID scale to determine the diagnosis of psychiatric co-morbidities in a relatively large sample, suggesting a higher rate. By comparing the status of individuals with TSC with typically developing children, the results suggests that neuropsychiatric co-morbidities are significantly higher in individuals with TSC. Research has revealed the frequent presence of two, three or more neuropsychiatric diseases in individuals with TSC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01814-4.

Tuberous Sclerosis Complex: Early Screening and Infant Outcome in NICU

OBJECTIVE

We describe the clinical and genetic features, drug use and neuropsychiatric disorders of infants diagnosed with tuberous sclerosis complex (TSC) within 3 months of age at a neonatal intensive care unit (NICU) to better understand the different outcomes from early screening.

METHODS

In this retrospective study, we consisted of 42 infants with a definitive TSC diagnosis by genetic criteria (TSC1 = 8, TSC2 = 34). The different phenotypes and outcomes between patients with TSC1 and TSC2 mutations were analyzed.

RESULTS

The most common initial presenting features of TSC were cortical tubers on magnetic resonance imaging (50%), hypomelanotic macules on skin (47.61%) and spasm (42.85%), when they were diagnosed. Following disease progression to time of follow-up 1 year later, we found that the rate of epilepsy increased from 42.85% to 75.61% and that of cardiac rhabdomyoma increased from 28.57% to 43.9%. The median age at first presentation was 7.84 ± 1.88 months. We also found that 54.83% of patients on medication were seizure free for over 1 year, and that 43.9% of patients have intellectual disability. In total, 42 variants of TSC were detected, including 12 novel variants. We found no evidence of an association between different clinical features and their outcomes among patients with different gene mutations.

CONCLUSION

Early diagnosis of TSC in NICU opens a window of opportunity for early, more effective treatment of epilepsy as well as reduces the risk of neurological conditions.

Quality of life in children with tuberous sclerosis complex: A pediatric cohort study

Aims

To evaluate the quality‐of‐life (QOL) impairment and identify the possible risk factors in patients with tuberous sclerosis complex (TSC) in China.

Methods

The parent proxy‐report PedsQL 4.0 Generic Core Scales were administered to 124 caregivers of children with TSC (aged 2‐18 years). For comparison, the survey was also conducted in a demographically group‐matched sample of healthy controls (HCs) (aged 2‐18 years).

Results

A total of 124 children with TSC and 206 HCs were recruited. The mean parent proxy‐report total scale score, physical health summary score, and psychosocial health summary score for children with TSC were 65.0 (SD 19.7), 77.6 (SD 22.9), and 58.0 (SD 21.3), respectively, compared with the HC values of 83.6 (SD 14.3), 87.2 (SD 16.9), and 82.8 (SD 15.9). There were statistically significant differences between the two groups (P < .0001). TSC2 mutation (P = .033), epilepsy (P = .011), seizure before 2 years old (P = .001), course of epilepsy (more than 2 years) (P = .001), high reported seizure frequency (more than once a month) (HRSF) (P = .007), multiple antiepileptic drugs (≥2) (P = .002), intellectual disability (ID) (mild and moderate ID, P < .0001, and severe and profound ID, P < .0001), and TANDs (P < .0001) (ADHD, P = .004; agoraphobia, P = .007; and social anxiety disorder, P < .0001) were closely related to lower QOL scores.

Conclusion

This study is the first large cohort study on QOL in children with TSC in China. The results of the PedsQL 4.0 indicated that the QOL of children with TSC is significantly lower than that of HCs. TSC2 mutation, epilepsy, early onset, long disease course and HRSF, ID, and TANDs are risk factors for poor QOL.