The mutational repertoire of uterine sarcomas and carcinosarcomas in a Brazilian cohort: A preliminary study

OBJECTIVES: The present study aimed to contribute to the catalog of genetic mutations involved in the carcinogenic processes of uterine sarcomas (USs) and carcinosarcomas (UCSs), which may assist in the accurate diagnosis of, and selection of treatment regimens for, these conditions. METHODS: We performed gene-targeted next-generation sequencing (NGS) of 409 cancer-related genes in 15 US (7 uterine leiomyosarcoma [ULMS], 7 endometrial stromal sarcoma [ESS], 1 adenosarcoma [ADS]), 5 UCS, and 3 uterine leiomyoma (ULM) samples. Quality, frequency, and functional filters were applied to select putative somatic variants. RESULTS: Among the 23 samples evaluated in this study, 42 loss-of-function (LOF) mutations and 111 missense mutations were detected, with a total of 153 mutations. Among them, 66 mutations were observed in the Catalogue of Somatic Mutations in Cancer (COSMIC) database. TP53 (48%), ATM (22%), and PIK3CA (17%) were the most frequently mutated genes. With respect to specific tumor subtypes, ESS showed mutations in the PDE4DIP, IGTA10, and DST genes, UCS exhibited mutations in ERBB4, and ULMS showed exclusive alterations in NOTCH2 and HER2. Mutations in the KMT2A gene were observed exclusively in ULM and ULMS. In silico pathway analyses demonstrated that many genes mutated in ULMS and ESS have functions associated with the cellular response to hypoxia and cellular response to peptide hormone stimulus. In UCS and ADS, genes with most alterations have functions associated with phosphatidylinositol kinase activity and glycerophospholipid metabolic process. CONCLUSION: This preliminary study observed pathogenic mutations in US and UCS samples. Further studies with a larger cohort and functional analyses will foster the development of a precision medicine-based approach for the treatment of US and UCS.

Identificação de mutações nos genes APC e MUTYH em famílias com polipose adenomatosa intestinal / Mutational screening of APC and MUTYH genes in families with adenomatous polyposis

Atualmente, pacientes com múltiplos adenomas colorretais são avaliados para mutações germinativas em dois genes, APC e MUTYH. Pacientes com mutações em APC apresentam Polipose Adenomatosa Familiar Clássica ou Atenuada (FAP/AFAP), enquanto que pacientes portadores de mutações bialélicas em MUTYH apresentam Polipose Associada ao MUTYH (MAP). O espectro das mutações em APC e MUTYH, assim como as correlações genótipo-fenótipo nestas síndromes, apresentam importante impacto clínico e podem ser distintas em cada população, tornando necessária a obtenção de dados genéticos e clínicos de diferentes populações. Além disso, cerca de 10-15% dos pacientes com polipose não apresentam mutações nesses genes, o que sugere a existência de outros genes de predisposição ainda desconhecidos. Assim, os objetivos deste estudo foram caracterizar mutações germinativas nos genes APC e MUTYH em pacientes Brasileiros com polipose, além de identificar novos genes associados com a síndrome através de sequenciamento de exoma dos pacientes negativos. No total, 23 pacientes não relacionados foram avaliados para mutações pontuais na região codificante dos genes APC e MUTYH através de sequenciamento capilar, e para rearranjos genômicos nos mesmos genes por meio de MLPA (Multiplex Ligation-Dependent Probe Amplification), arrays de hibridação genômica comparativa (CGH-array), e PCR duplex quantitativo. Este último método de avaliação do número de cópias genômicas foi desenvolvido e validado no presente estudo. Foram identificados 21 pacientes mutados nesta coorte (91%) - 6 pacientes apresentaram mutações patogênicas em MUTYH, 14 apresentaram mutações patogênicas em APC e um paciente foi portador de uma nova variante missense de significado clínico desconhecido em APC (p.Val1789Leu); seis mutações foram descritas pela primeira vez neste trabalho. Em um destes pacientes identificamos a primeira grande deleção genômica descrita no gene MUTYH. Correlações genótipo-fenótipo dos dados...

Patients with multiple colorectal adenomas are currently screened for germline mutations in two genes, APC and MUTYH. APC-mutated patients present classic or attenuated familial adenomatous polyposis (FAP/ AFAP), while patients carrying biallelic MUTYH mutations exhibit MUTYH-associated polyposis (MAP). The spectrum of APC and MUTYH mutations as well as the genotype-phenotype correlations in polyposis syndromes present clinical impact and can be population specific, making important to obtain genetic and clinical data from different populations. Furthermore, up to 10-15% of polyposis patients do not harbor mutations in these genes, suggesting that other yet unknown polyposis-predisposing genes could exist. Thus, the aim of this study was to characterize germline mutations in APC and MUTYH genes in Brazilian polyposis and to investigate novel susceptibility genes by exome sequencing of negative patients. At total, 23 unrelated polyposis patients were screened for APC/MUTYH point mutations through DNA capillary sequencing, and for APC and MUTYH genomic rearrangements through MLPA (multiplex ligation-dependent probe amplification), array-comparative genomic hybridization, and duplex quantitative PCR. This last gene dosage method was developed and validated in this study. We identified 21 mutated patients in this cohort (91%) – 6 patients carried MUTYH pathogenic mutations, 14 carried APC pathogenic mutations and one carried a novel APC missense variant of unknown clinical significance (p.Val1789Leu); six mutations were described for the first time in this series. One of these patients harbored the first large genomic deletion identified in MUTYH gene...