Clinical, pathological, and molecular correlation of folliculocystic and collagen hamartoma: A new potential diagnostic criterion for tuberous sclerosis complex?

Folliculocystic and collagen hamartoma (FCCH) is a rare entity with only 18 reported cases worldwide. Of them, most are found in patients diagnosed with tuberous sclerosis complex (TSC). FCCH has distinctive histopathologic features, including collagen deposition in the dermis, perifollicular fibrosis, and comedones with keratin-containing cysts lined by infundibular epithelium. We report three patients with a definitive TSC clinical diagnosis in whom clinical, histopathologic, and molecular features were studied to establish if there exists a genotype-phenotype correlation. The molecular results showed different heterozygous pathogenic variants (PV) in TSC2 in each patient: NM_000548.4:c.5024C>T, NG_005895.1:c.1599+1G>T, and NM_000548.4:c.2297_2298dup, to our knowledge; the latter PV has not been reported in public databases. The same PVs were identified as heterozygous in the tumor tissue samples, none of which yielded evidence of a TSC2 second hit. Because all FCCH patients with available molecular diagnosis carry a pathogenic genotype in TSC1 or TSC2, we suggest that FCCH should be considered as a new and uncommon diagnostic manifestation in the TSC consensus international diagnostic criteria. The early recognition of FCCH by clinicians could prompt the identification of new TSC cases. Interestingly, our molecular findings suggest that one of the patients described herein is a probable case of somatic mosaicism.

A novel mutation in the TSC2 gene protects against colorectal cancer in the Mexican population.

INTRODUCTION: Colorectal cancer (CRC) is a complex disease due to the large number of factors that influence its development, including variants in tumor suppressor genes. OBJECTIVE: To estimate allelic and genotypic frequencies of c.3915G>A and c.5371G>A variants of the TSC2 gene in a Mexican population with CRC, as well as to analyze their association with the development of CRC. METHODS: 126 peripheral blood samples from patients diagnosed with sporadic CRC and 134 from healthy individuals, regarded as the control group, were included. Identification of genotypes was carried out using traditional PCR and enzymatic digestion. All individuals signed an informed consent letter. RESULTS: The A allele of the c.3915G>A variant (OR = 0.31, 95% CI = 0.15-0.69, p = 0.004), as well as A/G haplotype of the c.3915G>A and c.5371G>A variants (OR = 0.28, 95% CI = 0.12-0.68, p = 0.005) showed a possible protective effect against sporadic CRC. In silico analysis indicated that both variants generate modifications in the splicing process. CONCLUSION: The presence of TSC2 gene c.3915G>A variant suggests a possible protective effect against sporadic CRC in the Mexican population; however, no association was observed with the c.5371G>A variant.

INTRODUCCIÓN: El cáncer colorrectal (CCR) es una enfermedad compleja debido al gran número de factores que influyen en su desarrollo, incluyendo variantes en genes supresores de tumores. OBJETIVO: Estimar las frecuencias alélicas y genotípicas de las variantes c.3915G>A y c.5371G>A del gen TSC2 en una población mexicana con CCR, así como analizar la asociación con el desarrollo de CCR. MÉTODOS: Se incluyeron 126 muestras de sangre periférica de pacientes con diagnóstico de CCR esporádico y 134 de individuos sanos, considerados como grupo de control. La identificación de los genotipos se llevó a cabo mediante PCR tradicional y digestión enzimática. Todos los individuos firmaron una carta de consentimiento informado. RESULTADOS: El alelo A de la variante c.3915G>A (RM = 0.31, IC 95 % = 0.15-0.69, p = 0.004), así como el haplotipo A/G de las variantes c.3915G>A y c.5371G>A (RM = 0.28, IC 95 % = 0.12-0.68, p = 0.005) mostraron un posible efecto protector contra CCR esporádico. El análisis in silico indicó que ambas variantes generan modificaciones en el proceso de corte y empalme. CONCLUSIÓN: La presencia de la variante c.3915G>A del gen TSC2 sugiere un posible efecto protector contra CCR esporádico en población mexicana; sin embargo, no se observó esta asociación con la variante c.5371G>A.

[Pulmonary lymphangioleiomyomatosis (LAM)]. / Pulmonale Lymphangioleiomyomatose (LAM).

Lymphangioleiomyomatosis (LAM) is a rare lung disease that mostly occurs in female patients. A total of 200-400 people are assumed to be infected in Germany. A sporadic form and a form associated with the tuberous sclerosis complex (TSC) can be separated. Mutations of the TSC­1 and TSC­2 genes are relevant. Morphologically, pulmonary multicysts and marginal micronodal proliferations of LAM cells are characteristic. Combinations with renal angiomyolipoma are typical and, in cases with TSC glioma, facial angiofibroma and ungual fibroma are seen. Prognosis is favorable (10-year survival: 80%) and with the use of mTORC1 inhibitors it could be improved. Lung transplantation can be considered in some cases.

[Renal carcinoma with leiomyomatous stroma and osseous metaplasia from a patient diagnosed with a tuberous sclerosis complex]. / Carcinome rénal à stroma léiomyomateux avec métaplasie osseuse chez un patient porteur d'une sclérose tubéreuse de Bourneville.

Renal cell carcinoma with leiomyomatous stroma is a rare and poorly described histopathological entity. Here we report a unique case with osseous metaplasia, in a 31-year-old man recently diagnosed with a tuberous sclerosis complex (TSC2 gene mutation). Partial nephrectomy was performed. Histologically, the epithelial component was made up of papillary and alveolar structures with clear to eosinophilic cytoplasm, and basally located nuclei. The cells are surrounded by an abundant smooth muscle stroma with focally osseous metaplasia. The tumor was positive for carbonic anhydrase IX, cytokeratin 7, cytokeratin 20, and CD10, and negative for TFE3. This emerging entity is highly correlated to tuberous sclerosis complex, which justifies a screening for the syndrome when this diagnosis is made.

A novel de novo splicing mutation c.1444-2A>T in the TSC2 gene causes exon skipping and premature termination in a patient with tuberous sclerosis syndrome.

Tuberous sclerosis complex (TSC) syndrome is a neurocutaneous syndrome that affects the brain, skin, and kidneys that has an adverse impact on the patient's health and quality of life. There have been several recent advances that elucidate the genetic complex of this disorder that will help understand the basic neurobiology of this disorder. We report a Tunisian patient with clinical manifestations of TSC syndrome. We investigated the causative molecular defect in this patient using PCR followed by direct sequencing. Subsequently, in silico studies and mRNA analysis were performed to study the pathogenicity of the new variation found in the TSC2. Bioinformatics tools predicted that the novel mutation c.1444-2A>T have pathogenic effects on splicing machinery. RT-PCR followed by sequencing revealed that the mutation c.1444-2A>T generates two aberrant transcripts. The first, with exon 15 skipping, is responsible for the loss of 52 amino acids, which causes the production of an aberrant protein isoform. The second, with the inclusion of 122 nucleotides of intron 14, is responsible for the creation of new premature termination codons (TGA), which causes the production of a truncated TSC2 protein. This study highlighted the clinical features of a Tunisian patient with TSC syndrome and revealed a splicing mutation c.1444-2A>T within intron 14 of TSC2 gene, which is present for the first time using Sanger sequencing approach, as a disease-causing mutation in a Tunisian patient with TSC syndrome.

A novel de novo mutation in the TSC2 gene in a Chinese patient with tuberous sclerosis complex.

Tuberous sclerosis complex (TSC), a multisystem genetic syndrome, often affects the central nervous system. The age of onset of TSC ranges from 0 to 15 years. The clinical features manifest as a combination of seizures, mental retardation, facial angiofibroma, renal angiomyolipoma, and cardiac rhabdomyoma. Most cases of TSC are caused by mutations of the TSC1 or TSC2 genes. We characterized a Chinese patient with a novel de novo mutation in the TSC2 gene associated with the TSC detected by next-generation sequencing.

The analysis of mutations and exon deletions at TSC2 gene in angiomyolipomas associated with tuberous sclerosis complex.

Angiomyolipomas (AMLs) are relatively rare hamartomatous or benign tumors that occasionally occur as part of tuberous sclerosis complex (TSC). Mutations in either of the two genes, TSC1 and TSC2, have been attributed to the development of TSC. Between 1994 and January 2009, 83 patients were diagnosed with AML at the Samsung Medical Center. In that group of patients, 5 (6%) had AML with TSC (AML-TSC). Mutational analysis of the TSC2 gene was performed using 7 samples from the 5 AML-TSC patients and 14 samples from 14 patients with sporadic AML without TSC (AML-non-TSC). From this analysis, mutations in TSC genes were identified in 5 samples from the AML-TSC patients (mutation detection rate=71%) and 3 samples from AML-non-TSC patients (mutation detection rate=21%). In the case of AML-TSC, 6 mutations were found including 3 recurrent mutations and 3 novel mutations, while in the case of AML-non-TSC, 4 mutations were identified once, including 1 novel mutation. Also MLPA analysis of the TSC2 gene showed that TSC2 exon deletion is more frequently observed in AML-TSC patients than in AML-non-TSC patients. This is the first mutation and multiplex ligation-dependent probe amplification (MLPA) analyses of TSC2 in Korean AMLs that focus on TSC. This study provides data that are representative of the distribution of mutations and exon deletions at TSC genes in clinically diagnosed AML-TSC cases of the Korean population.

Tuberous sclerosis complex associated lymphangioleiomyomatosis caused by de novo mutation of TSC2 gene in Vietnam: A case report.

Lymphangioleiomyomatosis (LAM) represents a rare, insidiously progressive disease of the pulmonary system, marked by cystic degradation of lung tissues leading to respiratory compromise. Pulmonary LAM has been identified as being associated with tuberous sclerosis complex (TSC) in its pulmonary manifestation (TSC-LAM), a multisystem genetic disorder resulting from mutations in either the TSC1 or TSC2 genes. Herein, we describe an early 20s female admitted to the hospital with dyspnea, chest pain, hypopigmented macules, and facial fibroadenomas. She has a medical history of renal angiomyolipomas (ALMs) and pneumothoraces. Diagnosis with LAM was confirmed through high-resolution computed tomography (HRCT) scan and histopathology of lung biopsy. Whole exome sequencing analysis identified a frameshift mutation c.4504del (p.L1502Cfs*74) in the patient's TSC2 gene. This variant was de novo due to its absence in the patient's parents. This is the first report on the clinical and genetic etiology of TSC-LAM in Vietnam.

The TSC2 c.2742+5G>A variant causes variable splicing changes and clinical manifestations in a family with tuberous sclerosis complex.

Background: Tuberous sclerosis complex (TSC) is a genetic, variably expressed, multisystem disease characterized by benign tumors. It is caused by pathogenic variants of the TSC complex subunit 1 gene (TSC1) and the TSC complex subunit 2 gene (TSC2). Genetic testing allows for early diagnosis, genetic counseling, and improved outcomes, but it did not identify a pathogenic variant in up to 25% of all TSC patients. This study aimed to identify the disease-causing variant in a Han-Chinese family with TSC. Methods: A six-member, three-generation Han-Chinese family with TSC and three unrelated healthy women were recruited. A comprehensive medical examination, a 3-year follow-up, whole exome sequencing, Sanger sequencing, and segregation analysis were performed in the family. The splicing analysis results obtained from six in silico tools, minigene assay, and patients' lymphocyte messenger RNA were compared, and quantitative reverse transcription PCR was used to confirm the pathogenicity of the variant. Results: Two affected family members had variable clinical manifestations including a rare bilateral cerebellar ataxia symptom. The 3-year follow-up results suggest the effects of a combined treatment of anti-epilepsy drugs and sirolimus for TSC-related epilepsy and cognitive deficits. Whole exome sequencing, Sanger sequencing, segregation analysis, splicing analysis, and quantitative reverse transcription PCR identified the TSC2 gene c.2742+5G>A variant as the genetic cause. This variant inactivated the donor splice site, a cryptic non-canonical splice site was used for different splicing changes in two affected subjects, and the resulting mutant messenger RNA may be degraded by nonsense-mediated decay. The defects of in silico tools and minigene assay in predicting cryptic splice sites were suggested. Conclusions: This study identified a TSC2 c.2742+5G>A variant as the genetic cause of a Han-Chinese family with TSC and first confirmed its pathogenicity. These findings expand the phenotypic and genetic spectrum of TSC and may contribute to its diagnosis and treatment, as well as a better understanding of the splicing mechanism.

De novo mutation of the TSC2 gene in patient with Tuberous Sclerosis Complex-Associated Neuropsychiatric Disorders (TAND) Phenotype: a case report.

Tuberous sclerosis complex (TSC) is a neurocutaneous disease caused by a mutation in the TSC1 or TSC2 gene. There are several neuropsychiatric manifestations associated with TSC known as TSC-associated neuropsychiatric disorder (TAND). This article concerns neuropsychiatric manifestations in children with the TSC2 gene mutation, with genetic analysis findings using whole-exome sequencing. Case: A 17-year-old girl presented with TSC, absence and focal epilepsy, borderline intellectual functioning, organic psychosis, and renal angiomyolipoma. She was emotionally unstable and preoccupied with irrelevant fears. In the physical examination, we found multiple hypomelanotic maculae, angiofibroma, and a shagreen patch. The intellectual assessment result with the Wechsler Adult Intelligence Scale at 17 was borderline intellectual functioning. Brain MRI showed cortical and subcortical tubers in the parietal and occipital lobes. Whole-exome sequencing was conducted, and the result was a missense mutation in exon 39 of the TSC2 gene [NM_000548.5:c.5024C>T (NP_000539.2:p.Pro1675Leu)]. The Sanger sequencing of the patient's parents revealed no mutations in the TSC2 gene, confirming the patient's de novo mutation. The patient was given several antiepileptic and antipsychotic drugs. Clinical discussion: Neuropsychiatric manifestation is a common phenotype in the TSC variant, and psychosis is one of the rare TAND symptoms in children. Conclusions: The neuropsychiatric phenotype and genotype in TSC patients are rarely reported and evaluated. We reported a female child with epilepsy, borderline intellectual functioning, and organic psychosis associated with a de novo mutation of the TSC2 gene. Organic psychosis is a rare symptom of TAND which also manifested in our patient.

TSC1 and TSC2 Gene Mutations in Chinese Tuberous Sclerosis Complex Patients Clinically Characterized by Epilepsy.

Objective: Tuberous sclerosis complex (TSC) is a multisystem disease. Variants in the TSC1 and TSC2 genes have been reported to be associated with TSC and are considered pathogenic. The purpose of this study was to determine the genetic mutations and expression patterns of TSC1 and TSC2 in 21 Chinese patients suffering from TSC who were clinically characterized by epilepsy. Methods: Peripheral blood samples were taken from 21 patients, their parents, and other family members. Their TSC1 and TSC2 genes were sequenced through next-generation sequencing to identify all variants. Results: We identified variants in 17/21 patients in either their TSC1 or TSC2 genes: 6 patients had TSC1 mutations and 11 had TSC2 mutations. There were 13 spontaneous mutations, and 3 that had been inherited from a parent. The mutations were classified by types: there were three missense mutations, five frameshift mutations, two splice site mutations, four nonsense mutations, two single codon deletions resulting the loss of an amino acid, and one large fragment deletion. Six of the mutations have not been previously reported. Conclusion: The genotypic analysis of Chinese TSC patients who are clinically characterized by epilepsy can potentially be useful for genetic counseling and prenatal diagnoses for patients and their families.

Screening for TSC1 and TSC2 mutations using NGS in Greek children with tuberous sclerosis syndrome.

Tuberous Sclerosis Complex (TSC) is a rare neurocutaneous syndrome inherited by an autosomal dominant manner. The disorder is commonly manifested by the presence of multiple benign tumors located in numerous tissues, including the brain, heart, skin and kidneys. Seizures, autism, developmental and behavioral delay, as well as non-neurological phenotypic findings, are suggestive of TSC. The identification of one pathogenic mutation in either the TSC1 or TSC2 genes is considered to be an independent diagnostic criterion. In our study, seventeen Greek patients, 2yo on average, were analyzed for the presence of pathogenic germline mutations in the aforementioned loci by Next-Generation Sequencing. A TSC1/2 gene panel was designed for the molecular diagnosis of the disease. Patients underwent initial diagnosis based on their clinical symptoms, most frequently involving the presence of skin lesions and/or epilepsy. Only one case was familial. Sixteen different genetic alterations were identified in TSC1 and TSC2 genes in fifteen patients, giving a 88% detection rate by employing NGS technology. Overall, most pathogenic mutations (11/15) identified were located in the TSC2 gene with exon 41 being the most frequent. With respect to genotype-phenotype association, no patient TSC1 (+) developed SEGA or renal cysts. No significant differences were observed between different types of TSC2 mutations and any clinical feature. Sequencing also revealed 18 different SNPs across the TSC1 and 20 across the TSC2 genes. This is the first registry of the genetic profile of TSC patients in Greece using a custom-made gene panel as molecular diagnostic tool.

Nueva mutación en el gen TSC2 protege contra el cáncer colorrectal en población mexicana / A novel mutation in the TSC2 gene protects against colorectal cancer in the Mexican population

Resumen Introducción: El cáncer colorrectal (CCR) es una enfermedad compleja debido al gran número de factores que influyen en su desarrollo, incluyendo variantes en genes supresores de tumores. Objetivo: Estimar las frecuencias alélicas y genotípicas de las variantes c.3915G>A y c.5371G>A del gen TSC2 en una población mexicana con CCR, así como analizar la asociación con el desarrollo de CCR. Métodos: Se incluyeron 126 muestras de sangre periférica de pacientes con diagnóstico de CCR esporádico y 134 de individuos sanos, considerados como grupo de control. La identificación de los genotipos se llevó a cabo mediante PCR tradicional y digestión enzimática. Todos los individuos firmaron una carta de consentimiento informado. Resultados: El alelo A de la variante c.3915G>A (RM = 0.31, IC 95 % = 0.15-0.69, p = 0.004), así como el haplotipo A/G de las variantes c.3915G>A y c.5371G>A (RM = 0.28, IC 95 % = 0.12-0.68, p = 0.005) mostraron un posible efecto protector contra CCR esporádico. El análisis in silico indicó que ambas variantes generan modificaciones en el proceso de corte y empalme. Conclusión: La presencia de la variante c.3915G>A del gen TSC2 sugiere un posible efecto protector contra CCR esporádico en población mexicana; sin embargo, no se observó esta asociación con la variante c.5371G>A.

Abstract Introduction: Colorectal cancer (CRC) is a complex disease due to the large number of factors that influence its development, including variants in tumor suppressor genes. Objective: To estimate allelic and genotypic frequencies of c.3915G>A and c.5371G>A variants of the TSC2 gene in a Mexican population with CRC, as well as to analyze their association with the development of CRC. Methods: 126 peripheral blood samples from patients diagnosed with sporadic CRC and 134 from healthy individuals, regarded as the control group, were included. Identification of genotypes was carried out using traditional PCR and enzymatic digestion. All individuals signed an informed consent letter. Results: The A allele of the c.3915G>A variant (OR = 0.31, 95% CI = 0.15-0.69, p = 0.004), as well as A/G haplotype of the c.3915G>A and c.5371G>A variants (OR = 0.28, 95% CI = 0.12-0.68, p = 0.005) showed a possible protective effect against sporadic CRC. In silico analysis indicated that both variants generate modifications in the splicing process. Conclusion: The presence of TSC2 gene c.3915G>A variant suggests a possible protective effect against sporadic CRC in the Mexican population; however, no association was observed with the c.5371G>A variant.