Germline mutation of TSC1 or TSC2 gene in Chinese patients with bilateral renal angiomyolipomas and mutation spectrum of Chinese TSC patients

Renal phenotypes correlate with genotypes in unrelated individuals with tuberous sclerosis complex in China

Purpose

To explore the relationship between the genotype and renal phenotype in a Chinese cohort and guide clinical decision-making for treating tuberous sclerosis complex (TSC).

Materials and methods

We reviewed 173 patients with definite TSC at three centers in China from September 2014 to September 2020. All the patients underwent TSC1 and TSC2 genetic testing as well as renal phenotypic evaluation. All analyses were performed using the SPSS software, version 19.0, with a cut-off P value of 0.05 considered statistically significant.

Results

We identified variants in 93% (161/173) cases, including 16% TSC1 and 77% TSC2 variants. Analysis of the relationship between the genotype and renal phenotype, revealed that those with TSC2 variants were more likely to develop severe renal AML (> 4) (P = 0.044). In terms of treatment, TSC2 variants were more likely to undergo nephrectomy/partial nephrectomy (P = 0.036) and receive mTOR medication such as everolimus (P < 0.001). However, there was no significant difference between the two groups in terms of their response to the everolimus treatment.

Conclusion

Patients with TSC2 variants exhibit more severe renal phenotypes, especially those associated with renal angiomyolipomas (AML), and they often require nephrectomy/partial nephrectomy or mTOR medication. Detection of the genotype is helpful in TSC management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02443-1.

Analysis of renal lesions in Chinese tuberous sclerosis complex patients with different types of TSC gene mutations

We sought to explore the relationship between renal lesion features and genetic mutations in tuberous sclerosis complex (TSC) patients. TSC patients with renal lesions were subjected to TSC1/2 gene next-generation sequencing (NGS). TSC1/2 mutation types and imaging examinations were screened for combined analysis of genetic and clinical features. Seventy-three probands among TSC patients with renal lesions were included. Twenty affected relatives were also included. In total, 93 patients were included. Eighty patients (86.0%) had bilateral renal angiomyolipomas (AMLs), and one had epithelioid AML. Two patients had polycystic kidney disease, one had renal cell carcinoma, and one had Wilms tumor. Among the 73 probands, four had TSC1 mutations, 53 had TSC2 mutations, and 16 had no mutations identified (NMI). There was no statistically significant difference between TSC1 mutation, TSC2 mutation and NMI group (P= 0.309), or between familial and sporadic groups (P= 0.775) when considering AML size. There was no statistically significant difference between pathogenic/likely pathogenic and benign/likely benign/NMI groups (P= 0.363) or among patients with different mutation types of TSC2 (P= 0.906). The relationship between the conditions of TSC gene mutations and the severity of renal lesions still needs more analysis. Patients with NMI, particularly those with familial disease, need more attention because the pathogenesis remains unknown.

Preliminary Screening of a Familial Tuberous Sclerosis Complex Pathogenic Gene

Purpose

The aim of this study was to screen the possible pathogenic genes of one family with tuberous sclerosis complexes (TSCs).

Patients and Methods

All family members were examined through detailed clinical evaluations, auxiliary examinations and CT. Then, we selected five members from this TSC family as the test samples. They were analysed by a new exon group sequencing method. Single nucleotide polymorphisms (SNPs) were screened by using databases, such as dbSNP and HAPMAP, and then the candidate genes were selected. Genes were analysed, and finally, the most likely mutation sites were screened. The results were examined by Sanger sequencing.

Results

In this TSC family, we identified c.913+2T>G, a splicing site mutation in the 9th intron region of TSC1. Family members without TSC did not have this mutation.

Conclusion

The mutations in the intron regions cannot be ruled out as a pathogenic factor for TSC.

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.

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.

Attacking the PI3K/Akt/mTOR signaling pathway for targeted therapeutic treatment in human cancer

Cancer is the second leading cause of human death globally. PI3K/Akt/mTOR signaling is one of the most frequently dysregulated signaling pathways observed in cancer patients that plays crucial roles in promoting tumor initiation, progression and therapy responses. This is largely due to that PI3K/Akt/mTOR signaling is indispensable for many cellular biological processes, including cell growth, metastasis, survival, metabolism, and others. As such, small molecule inhibitors targeting major kinase components of the PI3K/Akt/mTOR signaling pathway have drawn extensive attention and been developed and evaluated in preclinical models and clinical trials. Targeting a single kinase component within this signaling usually causes growth arrest rather than apoptosis associated with toxicity-induced adverse effects in patients. Combination therapies including PI3K/Akt/mTOR inhibitors show improved patient response and clinical outcome, albeit developed resistance has been reported. In this review, we focus on revealing the mechanisms leading to the hyperactivation of PI3K/Akt/mTOR signaling in cancer and summarizing efforts for developing PI3K/Akt/mTOR inhibitors as either mono-therapy or combination therapy in different cancer settings. We hope that this review will facilitate further understanding of the regulatory mechanisms governing dysregulation of PI3K/Akt/mTOR oncogenic signaling in cancer and provide insights into possible future directions for targeted therapeutic regimen for cancer treatment, by developing new agents, drug delivery systems, or combination regimen to target the PI3K/Akt/mTOR signaling pathway. This information will also provide effective patient stratification strategy to improve the patient response and clinical outcome for cancer patients with deregulated PI3K/Akt/mTOR signaling.