RESUMEN
BACKGROUND: Rhabdoid tumors (RT) are aggressive, rare tumors predominantly affecting young children, characterized by bi-allelic SMARCB1 gene inactivation. While most SMARCB1 alterations are acquired de novo, a third of cases exhibit germline alterations, defining Rhabdoid Tumors Predisposition Syndrome (RTPS1). With increased sensitivity of next-generation sequencing (NGS), mosaicisms in genes linked to genetic diseases are more detectable. This study focuses on exploring SMARCB1 germline alterations, notably mosaicism in blood samples of children with RT and in parents, using a custom NGS panel. METHODS: A cohort of 280 children and 140 parents with germline analysis was studied. Germline DNA from 111 children with RT and 32 parents were re-analyzed with a custom NGS panel with 1,500X average depth targeting the SMARCB1 gene to identify intragenic variants not detected with conventional low-sensitivity methods. Follow-up data was obtained for 77 patients. RESULTS: Nine previously undetected mosaicism cases were identified, totaling 17/280 patients with a mosaic variant (6.1%) in the cohort, with variant allele frequencies between 0.9% and 33%, thus highlighting the prior underestimation of its prevalence. Follow-up data showed that 4 out of 7 survivors with mosaic variants developed distinct novel tumors, two sharing SMARCB1 alterations with the initial tumor, emphasizing the potential clinical impact of SMARCB1 mosaicism. CONCLUSIONS: The hitherto underestimated rate of SMARCB1 mosaicism in RT underscores the need for optimized genetic counseling and oncological monitoring. The findings have significant medical implications, considering the dire prognosis of RT.
RESUMEN
Background: ELP1 pathogenic variants (PV) have been recently identified as the most frequent variants predisposing to Sonic Hedgehog (SHH) medulloblastomas (MB); however, guidelines are still lacking for genetic counseling in this new syndrome. Methods: We retrospectively reviewed clinical and genetic data of a French series of 29 ELP1-mutated MB. Results: All patients developed SHH-MB, with a biallelic inactivation of PTCH1 found in 24 tumors. Other recurrent alterations encompassed the TP53 pathway and activation of MYCN/MYCL signaling. The median age at diagnosis was 7.3 years (range: 3-14). ELP1-mutated MB behave as sporadic cases, with similar distribution within clinical and molecular risk groups and similar outcomes (5 y - OSâ =â 86%); no unusual side effect of treatments was noticed. Remarkably, a germline ELP1 PV was identified in all patients with available constitutional DNA (nâ =â 26); moreover, all tested familial trio (nâ =â 11) revealed that the PVs were inherited. Two of the 26 index cases from the French series had a family history of MB; pedigrees from these patients and from 1 additional Dutch family suggested a weak penetrance. Apart from MB, no cancer was associated with ELP1 PVs; second tumors reported in 4 patients occurred within the irradiation fields, in the usual time-lapse for expected radiotherapy-induced neoplasms. Conclusions: The low penetrance, the "at risk' age window limited to childhood and the narrow tumor spectrum, question the actual benefit of genetic screening in these patients and their family. Our results suggest restricting ELP1 germline sequencing to patients with SHH-MB, depending on the parents" request.
RESUMEN
Inversions, i.e. a change in orientation of a segment of DNA, are a recognized cause of human diseases which remain overlooked due to their balanced nature. Inversions can have severe or more subtle impacts on gene expression. We describe two families that exemplify these aspects and underline the need for inversion detection in routine diagnosis. The first family (F1) displayed a sibship with two constitutional mismatch repair deficiency patients and a family history of colon cancer in the paternal branch. The second family (F2) displayed a severe history of Lynch syndrome. These families were analyzed using a whole gene panel (WGP) strategy i.e. including colon cancer genes with their intronic and flanking genomic regions. In F1, a PMS2 inversion encompassing the promoter region to intron 1 and a PMS2 splice variant were found in the maternal and paternal branch, respectively. In F2, we described the first MSH6 inversion, involving the 5' part of MSH6 and the 3' part of the nearby gene ANXA4. Inversion detection mandates genomic sequencing, but makes a valuable contribution to the diagnostic rate. WGP is an attractive strategy as it maximizes the detection power on validated genes and keeps sufficient depth to detect de novo events.
Asunto(s)
Neoplasias del Colon , Neoplasias Colorrectales Hereditarias sin Poliposis , Neoplasias Colorrectales , Síndromes Neoplásicos Hereditarios , Humanos , Endonucleasa PMS2 de Reparación del Emparejamiento Incorrecto/genética , Proteínas de Unión al ADN/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales/genética , Reparación de la Incompatibilidad de ADN/genética , Proteína 2 Homóloga a MutS/genética , Homólogo 1 de la Proteína MutL/genéticaRESUMEN
BACKGROUND: The interpretation of germline TP53 variants is critical to ensure appropriate medical management of patients with cancer and follow-up of variant carriers. This interpretation remains complex and is becoming a growing challenge considering the exponential increase in TP53 tests. We developed a functional assay directly performed on patients' blood. METHODS: Peripheral blood mononuclear cells were cultured, activated, exposed to doxorubicin and the p53-mediated transcriptional response was quantified using reverse transcription-multiplex ligation probe amplification and RT-QMPSF assays, including 10 p53 targets selected from transcriptome analysis, and two amplicons to measure p53 mRNA levels. We applied this blood functional assay to 77 patients addressed for TP53 analysis. RESULTS: In 51 wild-type TP53 individuals, the mean p53 functionality score was 12.7 (range 7.5-22.8). Among eight individuals harbouring likely pathogenic or pathogenic variants, the scores were reduced (mean 4.8, range 3.1-7.1), and p53 mRNA levels were reduced in patients harbouring truncating variants. We tested 14 rare unclassified variants (p.(Pro72His), p.(Gly105Asp), p.(Arg110His), p.(Phe134Leu), p.(Arg158Cys), p.(Pro191Arg), p.(Pro278Arg), p.(Arg283Cys), p.(Leu348Ser), p.(Asp352Tyr), p.(Gly108_Phe109delinsVal), p.(Asn131del), p.(Leu265del), c.-117G>T) and 12 yielded functionally abnormal scores. Remarkably, the assay revealed that the c.*1175A>C polymorphic variant within TP53 poly-adenylation site can impact p53 function with the same magnitude as a null variant, when present on both alleles, and may act as a modifying factor in pathogenic variant carriers. CONCLUSION: This blood p53 assay should therefore be a useful tool for the rapid clinical classification of germline TP53 variants and detection of non-coding functional variants.
Asunto(s)
Análisis Mutacional de ADN/métodos , Predisposición Genética a la Enfermedad/genética , Mutación de Línea Germinal , Neoplasias/genética , Proteína p53 Supresora de Tumor/genética , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Genotipo , Humanos , Leucocitos Mononucleares/metabolismo , Masculino , Persona de Mediana Edad , Neoplasias/patología , Polimorfismo de Nucleótido Simple , Reproducibilidad de los Resultados , Proteína p53 Supresora de Tumor/sangre , Adulto JovenRESUMEN
BACKGROUND: The incidence of pancreatic ductal adenocarcinoma (PDAC) is increasing sharply. The survival of patients with metastases is usually about a year. However, the occurrence of isolated lung metastases after resection of the primary tumor, although rare, seems to indicate a better prognosis, with an average survival ranging from 40 to 80 months. KRAS, TP53, CDK2NA, and SMAD4 are the most common driver genes in pancreatic adenocarcinoma. OBJECTIVE: Our objectives were to determine whether a link exists between survival and mutations of driver genes in patients with isolated pulmonary metastases. METHODS: All patients who underwent curative surgery in our institution between 2010 and 2018 were included in the study. From these, we identified patients for whom recurrence was only pulmonary and those with metastases at other sites. KRAS, TP53, CDK2NA, and SMAD4 were analyzed on the primary tumor of patients with pulmonary metastases. RESULTS: Among 233 patients diagnosed with PDAC in our institution over 8 years, 41 (17.5%) underwent curative surgery. Of these, seven (3%) developed isolated pulmonary metastases, 32 developed other metastases, and two did not recur. Median survival was 59 months for patients with isolated lung metastases and 25.3 months for patients with metastases at other sites. An absence of mutations of two driver genes in primary tumors (CDK2NA and SMAD4) was observed in patients with isolated pulmonary metastases. CONCLUSIONS: The absence of mutations in the CDK2NA and SMAD4 tumor-suppressor genes in patients with isolated pulmonary metastases contrasts with the commonly observed high rates of driver gene mutations and suggests a link with overall survival.
Asunto(s)
Adenocarcinoma/genética , Neoplasias Pulmonares/genética , Mutación/genética , Neoplasias Pancreáticas/genética , Adenocarcinoma/patología , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/genética , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Femenino , Estudios de Seguimiento , Humanos , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/patología , Neoplasias Pancreáticas/patología , Pronóstico , Estudios Retrospectivos , Proteína Smad4/genéticaRESUMEN
The rate of genetic diagnosis of French patients with familial pancreatic ductal adenocarcinoma (PDAC) is not known. We report germline genetic testing data from 133 index cases meeting criteria for familial pancreatic cancer (FPC) as well as 87 'FPC-like' index cases who did not fulfilled strict FPC definition but were evocative for a PDAC predisposition. The overall rate of genetic diagnosis (in BRCA1, BRCA2, CDKN2A, and ATM genes) was 8.3% in FPC patients and 4.6% in FPC-like patients, consistent with the literature in other populations. Genetic variants were also identified in FANCA and BAP1 genes, as well as in the CDKN2A p12 transcript. This pancreas-specific transcript is a known key player in driving pancreatic oncogenesis. This might be the first described case of a PDAC genetic predisposition due to a variant in this specific transcript.
Asunto(s)
Carcinoma/genética , Pruebas Genéticas , Células Germinativas/metabolismo , Neoplasias Pancreáticas/genética , Adulto , Anciano , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proteínas de Neoplasias/genética , Adulto JovenRESUMEN
In oncology, the expanding use of multi-gene panels to explore familial cancer predisposition and tumor genome analysis has led to increased secondary findings discoveries (SFs) and has given rise to important medical, ethical, and legal issues. The American College of Medical Genetics and Genomics published a policy statement for managing SFs for a list of genes, including 25 cancer-related genes. Currently, there are few recommendations in Europe. From June 2016 to May 2017, the French Society of Predictive and Personalized Medicine (SFMPP) established a working group of 47 experts to elaborate guidelines for managing information given on the SFs for genes related to cancers. A subgroup of ethicists, lawyers, patients' representatives, and psychologists provided ethical reflection, information guidelines, and materials (written consent form and video). A subgroup with medical expertise, including oncologists and clinical and molecular geneticists, provided independent evaluation and classification of 60 genes. The main criteria were the "actionability" of the genes (available screening or prevention strategies), the risk evaluation (severity, penetrance, and age of disease onset), and the level of evidence from published data. Genes were divided into three classes: for class 1 genes (n = 36), delivering the information on SFs was recommended; for class 2 genes (n = 5), delivering the information remained questionable because of insufficient data from the literature and/or level of evidence; and for class 3 genes (n = 19), delivering the information on SFs was not recommended. These guidelines for managing SFs for cancer-predisposing genes provide new insights for clinicians and laboratories to standardize clinical practices.
Asunto(s)
Revelación/normas , Pruebas Genéticas/normas , Neoplasias/genética , Guías de Práctica Clínica como Asunto , Análisis de Secuencia de ADN/normas , Revelación/ética , Revelación/legislación & jurisprudencia , Francia , Humanos , Neoplasias/diagnóstico , Medicina de Precisión/normas , Sociedades MédicasRESUMEN
Importance: Genetic testing for melanoma-prone mutation in France, a country with low to moderate incidence of melanoma, is proposed in cases with 2 invasive cutaneous melanomas and/or related cancers in the same patient, or in first- or second-degree relatives (rule of 2). In preclinical studies, these rules led to disclosure of mutation(s) in more than 10% of these families, the threshold widely accepted to justify genetic testing for cancers. Objective: To reconsider these criteria in a general population testing of patients. Design, Setting, and Participants: This was a retrospective study, performed from 2004 to 2015 at Angers and Lyons University Hospitals, of a cohort of 1032 patients who underwent genetic testing. Main Outcomes and Measures: Frequency of mutation in high (CDKN2A, CDK4, and BAP1) and intermediate (MITF) susceptibility genes; statistical effect of histologic subtype, age, dysplastic nevi syndrome, and associated cancers on mutation rate; and evaluation of cases with anamnestic uncertainty. Results: The mutation rate was 67 of 1032 patients (6.5%). Their mean (SD) age was 54.5 (14.2) years [range, 18-89 years], and 543 (52.6%) were men. It increased to 38 of 408 patients (9.3%) when applying a rule of 3 (those with ≥3 primary melanomas or genetically related cancers) (P = .68) and to 27 of 150 patients (18.0%) with a rule of 4 (4 primary melanomas or related cancer) (P < .001). The impact of age at first melanoma was observed only in those younger than 40 years, with a rate of 32 of 263 (12.1%) (P = .12) for the rule of 2 and 22 of 121 (18.2%) (P = .001) for the rule of 3. Use of the rule of 2 in patients younger than 40 years reduced the number of missed CDKN2A-mutated-families when applying the rule of 3 from 14 of 43 to 7 of 43. Anamnestic uncertainty, found in 88 families (8.5%), if excluded, would have led us to withdraw of only 21 cases (23.8%), and only 1 mutation would have been missed. Conclusions and Relevance: We propose using the rule of 3 to recommend genetic testing in France and countries with low to moderate incidence of melanoma, except in families and patients with a first melanoma occurrence before age 40 years in whom the rule of 2 could be maintained.
Asunto(s)
Predisposición Genética a la Enfermedad , Pruebas Genéticas/métodos , Melanoma/diagnóstico , Neoplasias Cutáneas/diagnóstico , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Quinasa 4 Dependiente de la Ciclina/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina , Inhibidor p18 de las Quinasas Dependientes de la Ciclina/genética , Síndrome del Nevo Displásico/genética , Femenino , Francia/epidemiología , Hospitales Universitarios , Humanos , Incidencia , Masculino , Melanoma/epidemiología , Melanoma/genética , Factor de Transcripción Asociado a Microftalmía/genética , Persona de Mediana Edad , Mutación , Estudios Retrospectivos , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/genética , Proteínas Supresoras de Tumor/genética , Ubiquitina Tiolesterasa/genética , Adulto JovenRESUMEN
BACKGROUND: Sarcomas are rare mesenchymal malignancies whose pathogenesis is poorly understood; both environmental and genetic risk factors could contribute to their aetiology. METHODS AND RESULTS: We performed whole-exome sequencing (WES) in a familial aggregation of three individuals affected with soft-tissue sarcoma (STS) without TP53 mutation (Li-Fraumeni-like, LFL) and found a shared pathogenic mutation in CDKN2A tumour suppressor gene. We searched for individuals with sarcoma among 474 melanoma-prone families with a CDKN2A-/+ genotype and for CDKN2A mutations in 190 TP53-negative LFL families where the index case was a sarcoma. Including the initial family, eight independent sarcoma cases carried a germline mutation in the CDKN2A/p16INK4A gene. In five out of seven formalin-fixed paraffin-embedded sarcomas, heterozygosity was lost at germline CDKN2A mutations sites demonstrating complete loss of function. As sarcomas are rare in CDKN2A/p16INK4A carriers, we searched in constitutional WES of nine carriers for potential modifying rare variants and identified three in platelet-derived growth factor receptor (PDGFRA) gene. Molecular modelling showed that two never-described variants could impact the PDGFRA extracellular domain structure. CONCLUSION: Germline mutations in CDKN2A/P16INK4A, a gene known to predispose to hereditary melanoma, pancreatic cancer and tobacco-related cancers, account also for a subset of hereditary sarcoma. In addition, we identified PDGFRA as a candidate modifier gene.
Asunto(s)
Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Inhibidor p18 de las Quinasas Dependientes de la Ciclina/genética , Genes p16 , Mutación de Línea Germinal , Sarcoma/genética , Neoplasias de los Tejidos Blandos/genética , Femenino , Determinismo Genético , Predisposición Genética a la Enfermedad , Heterocigoto , Humanos , Masculino , Linaje , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/genética , Secuenciación del ExomaRESUMEN
AIM: To evaluate the risk associated with variants of the UNC5C gene recently suspected to predispose to familial colorectal cancer (CRC). METHODS: We screened patients with familial CRC forms as well as patients with sporadic CRCs. In a first time, we analyzed exon 11 of the UNC5C gene in 120 unrelated patients with suspected hereditary CRC, 58 patients with suspected Lynch-associated cancer or polyposis, and 132 index cases of Lynch syndrome families with a characterized mutation in a DNA mismatch repair (MMR). Next, 1023 patients with sporadic CRC and 1121 healthy individuals were screened for the variants identified in patients with familial cancer. RESULTS: Of 120 patients with familial CRC of unknown etiology, one carried the previously reported mis-sense mutation p.Arg603Cys (R603C) and another exhibited the unreported variant of unknown significance p.Thr617Ile (T617I). The p.Ala628Lys (A628K) mutation previously described as the main UNC5C risk variant for familial CRC was not detected in any cases of familial CRC of unknown etiology, but was present in a patient with familial gastric cancer and in two Lynch syndrome patients in co-occurrence with MMR mutations. A statistically non-significant increase in cancer risk was identified in familial CRC and/or other Lynch-associated cancers (1/178 patients vs 2/1121 healthy controls, OR = 3.2, 95%CI: 0.29-35.05, P = 0.348) and in sporadic CRCs (4/1023 patients vs 2/1121 healthy controls, OR = 2.2, 95%CI: 0.40-12.02, P = 0.364). CONCLUSION: We confirm that UNC5C mutations are very rare in familial and sporadic CRCs, but further investigations are needed to justify routine UNC5C testing for diagnostic purposes.
Asunto(s)
Poliposis Adenomatosa del Colon/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Mutación , Receptores de Superficie Celular/genética , Poliposis Adenomatosa del Colon/patología , Adulto , Anciano , Estudios de Casos y Controles , Neoplasias Colorrectales Hereditarias sin Poliposis/patología , Exones , Femenino , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Herencia , Humanos , Masculino , Persona de Mediana Edad , Receptores de Netrina , Oportunidad Relativa , Linaje , Fenotipo , Medición de Riesgo , Factores de RiesgoRESUMEN
We describe a patient with a Homo sapiens mutL homolog 1 (MLH1)-associated Lynch syndrome with previous diagnoses of two distinct primary cancers: a sigmoid colon cancer at the age of 39 years, and a right colon cancer at the age of 50 years. The mutation identified in his blood and buccal cells, c.1771delG, p.Asp591Ilefs*25, appears to be a de novo event, as it was not transmitted by either of his parents. This type of de novo event is rare in MLH1 as only three cases have been reported in the literature so far. Furthermore, the discordant results observed between replication error phenotyping and immunohistochemistry highlight the importance of the systematic use of both pre-screening tests in the molecular diagnosis of Lynch syndrome.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Mutación de Línea Germinal , Proteínas Nucleares/genética , Adulto , Femenino , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Homólogo 1 de la Proteína MutL , LinajeRESUMEN
INTRODUCTION: Breast carcinoma is the main malignant tumor occurring in patients with Cowden disease, a cancer-prone syndrome caused by germline mutation of the tumor suppressor gene PTEN characterized by the occurrence throughout life of hyperplastic, hamartomatous and malignant growths affecting various organs. The absence of known histological features for breast cancer arising in a PTEN-mutant background prompted us to explore them for potential new markers. METHODS: We first performed a microarray study of three tumors from patients with Cowden disease in the context of a transcriptomic study of 74 familial breast cancers. A subsequent histological and immunohistochemical study including 12 additional cases of Cowden disease breast carcinomas was performed to confirm the microarray data. RESULTS: Unsupervised clustering of the 74 familial tumors followed the intrinsic gene classification of breast cancer except for a group of five tumors that included the three Cowden tumors. The gene expression profile of the Cowden tumors shows considerable overlap with that of a breast cancer subgroup known as molecular apocrine breast carcinoma, which is suspected to have increased androgenic signaling and shows frequent ERBB2 amplification in sporadic tumors. The histological and immunohistochemical study showed that several cases had apocrine histological features and expressed GGT1, which is a potential new marker for apocrine breast carcinoma. CONCLUSIONS: These data suggest that activation of the ERBB2-PI3K-AKT pathway by loss of PTEN at early stages of tumorigenesis promotes the formation of breast tumors with apocrine features.