Discovery of recessive effect of human polymerase δ proofreading deficiency through mutational analysis of POLD1-mutated normal and cancer cells.

Constitutional heterozygous pathogenic variants in the exonuclease domain of POLE and POLD1, which affect the proofreading activity of the corresponding polymerases, cause a cancer predisposition syndrome characterized by increased risk of gastrointestinal polyposis, colorectal cancer, endometrial cancer and other tumor types. The generally accepted explanation for the connection between the disruption of the proofreading activity of polymerases epsilon and delta and cancer development is through an increase in the somatic mutation rate. Here we studied an extended family with multiple members heterozygous for the pathogenic POLD1 variant c.1421T>C p.(Leu474Pro), which segregates with the polyposis and cancer phenotypes. Through the analysis of mutational patterns of patient-derived fibroblasts colonies and de novo mutations obtained by parent-offspring comparisons, we concluded that heterozygous POLD1 L474P just subtly increases the somatic and germline mutation burden. In contrast, tumors developed in individuals with a heterozygous mutation in the exonuclease domain of POLD1, including L474P, have an extremely high mutation rate (>100 mut/Mb) associated with signature SBS10d. We solved this contradiction through the observation that tumorigenesis involves somatic inactivation of the wildtype POLD1 allele. These results imply that exonuclease deficiency of polymerase delta has a recessive effect on mutation rate.

Genetic and clinical characterization of a novel FH founder mutation in families with hereditary leiomyomatosis and renal cell cancer syndrome.

BACKGROUND: Hereditary leiomyomatosis and renal cell cancer syndrome is a rare autosomal dominant hereditary syndrome. Previously, we published the largest cohort of FH mutation carriers in Spain and observed a highly recurrent missense heterozygous variant, FH(NM_000143.4):c.1118A > G p.(Asn373Ser), in 104 individuals from 31 apparently unrelated families. Here, we aimed to establish its founder effect and characterize the associated clinical phenotype. RESULTS: Haplotype analysis confirmed that families shared a common haplotype (32/38 markers) spanning 0.61-0.82 Mb, indicating this recurrent variant was inherited from a founder ancestor. Cutaneous and uterine leiomyomatosis were diagnosed in 64.6% (64/99) and 98% (50/51) of patients, respectively, and renal cell cancer was present in 10.4% (10/96). The pathogenic FH_c.1118A > G variant is a Spanish founder mutation that originated 12-26 generations ago. We estimate that the variant may have appeared between 1370 and 1720. Individuals carrying this founder mutation had similar frequency of renal cell cancer and a higher frequency of renal cysts and leiomyomas than those in other cohorts of this syndrome. CONCLUSIONS: In the Spanish province of Alicante there is a high prevalence of HLRCC because of the founder mutation FH c.1118A > G; p.(Asn373Ser). The characterization of founder mutations provides accurate and specific information regarding their penetrance and expressivity. In individuals with suspected HLRCC from the province of Alicante, genetic testing by direct analysis of the founder FH c.1118A > G; p.(Asn373Ser) mutation may be a faster and more efficient diagnostic tool compared with complete gene sequencing.

Prevalence of Homologous Recombination Deficiency Among Patients With Germline RAD51C/D Breast or Ovarian Cancer.

Importance: RAD51C and RAD51D are involved in DNA repair by homologous recombination. Germline pathogenic variants (PVs) in these genes are associated with an increased risk of ovarian and breast cancer. Understanding the homologous recombination deficiency (HRD) status of tumors from patients with germline PVs in RAD51C/D could guide therapeutic decision-making and improve survival. Objective: To characterize the clinical and tumor characteristics of germline RAD51C/D PV carriers, including the evaluation of HRD status. Design, Setting, and Participants: This retrospective cohort study included 91 index patients plus 90 relatives carrying germline RAD51C/D PV (n = 181) in Spanish hospitals from January 1, 2014, to December 31, 2021. Genomic and functional HRD biomarkers were assessed in untreated breast and ovarian tumor samples (n = 45) from June 2022 to February 2023. Main Outcomes and Measures: Clinical and pathologic characteristics were assessed using descriptive statistics. Genomic HRD by genomic instability scores, functional HRD by RAD51, and gene-specific loss of heterozygosity were analyzed. Associations between HRD status and tumor subtype, age at diagnosis, and gene-specific loss of heterozygosity in RAD51C/D were investigated using logistic regression or the t test. Results: A total of 9507 index patients were reviewed, and 91 patients (1.0%) were found to carry a PV in RAD51C/D; 90 family members with a germline PV in RAD51C/D were also included. A total of 157 of carriers (86.7%) were women and 181 (55.8%) had received a diagnosis of cancer, mainly breast cancer or ovarian cancer. The most prevalent PVs were c.1026+5_1026+7del (11 of 56 [19.6%]) and c.709C>T (9 of 56 [16.1%]) in RAD51C and c.694C>T (20 of 35 [57.1%]) in RAD51D. In untreated breast cancer and ovarian cancer, the prevalence of functional and genomic HRD was 55.2% (16 of 29) and 61.1% (11 of 18) for RAD51C, respectively, and 66.7% (6 of 9) and 90.0% (9 of 10) for RAD51D. The concordance between HRD biomarkers was 91%. Tumors with the same PV displayed contrasting HRD status, and age at diagnosis did not correlate with the occurrence of HRD. All breast cancers retaining the wild-type allele were estrogen receptor positive and lacked HRD. Conclusions and Relevance: In this cohort study of germline RAD51C/D breast cancer and ovarian cancer, less than 70% of tumors displayed functional HRD, and half of those that did not display HRD were explained by retention of the wild-type allele, which was more frequent among estrogen receptor-positive breast cancers. Understanding which tumors are associated with RAD51C/D and HRD is key to identify patients who can benefit from targeted therapies, such as PARP (poly [adenosine diphosphate-ribose] polymerase) inhibitors.

SEOM clinical guideline on heritable TP53-related cancer syndrome (2022)

Li-Fraumeni syndrome is caused by heterozygous germline pathogenic variants in the TP53 gene. It involves a high risk of a variety of malignant tumors in childhood and adulthood, the main ones being premenopausal breast cancer, soft tissue sarcomas and osteosarcomas, central nervous system tumors, and adrenocortical carcinomas. The variability of the associated clinical manifestations, which do not always fit the classic criteria of Li-Fraumeni syndrome, has led the concept of SLF to extend to a more overarching cancer predisposition syndrome, termed hereditable TP53-related cancer syndrome (hTP53rc). However, prospective studies are needed to assess genotype–phenotype characteristics, as well as to evaluate and validate risk-adjusted recommendations. This guideline aims to establish the basis for interpreting pathogenic variants in the TP53 gene and provide recommendations for effective screening and prevention of associated cancers in carrier individuals (AU)

Uso de paneles de genes en pacientes con alto riesgo de cáncer digestivo hereditario: documento de posicionamiento de la AEG, SEOM, AEGH y consorcio IMPaCT-GENÓMICA / Use of multi-gene panels in patients at high risk of hereditary digestive cancer: position statement of AEG, SEOM, AEGH and IMPaCT-GENÓMICA consortium

Este documento de posicionamiento, auspiciado por la Asociación Española de Gastroenterología, la Sociedad Española de Oncología Médica, la Asociación Española de Genética Humana y el consorcio IMPaCT-Genómica, tiene como objetivo realizar recomendaciones para el uso de paneles de genes en la evaluación de individuos con alto riesgo de cáncer digestivo hereditario. Para medir la calidad de la evidencia y los niveles de recomendación se ha utilizado la metodología basada en el sistema Grading of Recommendations Assessment, Development and Evaluation (GRADE). Se obtuvo el consenso entre expertos mediante un método Delphi. El documento incluye recomendaciones sobre escenarios clínicos en los que se recomienda el uso de paneles de genes en cáncer colorrectal, síndromes polipósicos, cáncer gástrico y pancreático, así como los genes de los paneles a ser considerados en cada una de estas situaciones clínicas. También se establecen recomendaciones sobre la evaluación de mosaicismos, las estrategias de asesoramiento ante la ausencia de sujeto índice y, finalmente, el análisis constitucional tras identificación de variantes patogénicas tumorales. (AU)

This position statement, sponsored by the Asociación Española de Gastroenterología, the Sociedad Española de Oncología Médica, the Asociación Española de Genética Humana and the IMPaCT-Genómica Consortium aims to establish recommendations for use of multi-gene panel testing in patients at high risk of hereditary gastrointestinal and pancreatic cancer. To rate the quality of the evidence and the levels of recommendation, we used the methodology based on the GRADE system (Grading of Recommendations Assessment, Development and Evaluation). We reached a consensus among experts using a Delphi method. The document includes recommendations on clinical scenarios where multi-gene panel testing is recommended in colorectal cancer, polyposis syndromes, gastric and pancreatic cancer, as well as the genes to be considered in each clinical scenario. Recommendations on the evaluation of mosaicisms, counseling strategies in the absence of an index subject and, finally, constitutional analysis after identification of pathogenic tumor variants are also made. (AU)

Paraganglioma vesical. Reporte de dos casos clínicos y revisión de la literatura / Bladder paraganglioma. Report of two clinical cases and review of the literature

Objetivos: Descripción de dos casos incidentales de paraganglioma vesical en mujeres y revisiónde la literatura publicada. Métodos: Se realizó una búsqueda bibliográfica en Medline en los últimos 10 años según los términos “urinary bladder” y “paraganglioma”. Resultados: El paraganglioma vesical representa menos del 0,06% de los tumores vesicales y el 10% de todos los paragangliomas. Suelen ser esporádicos, pudiendo también asociarse a síndromes de predisposición hereditaria como el síndrome de paraganglioma – feocromocitoma hereditario. Dada su baja frecuencia, no existen pautas de manejo. Su riesgo de malignización obliga a un seguimiento a largo plazo. El estudio de mutaciones germinales mediante secuenciación masiva descartó la asociación a un síndrome hereditario. El manejo inicial incluyó reevaluación temprana mediante cistoscopia, resección transuretral vesical (RTU – V) e imagen. Conclusiones: Los paragangliomas vesicales son neoplasias infrecuentes que pueden asociarse a síndromes hereditarios. Su tratamiento y seguimiento deberían basarse en un enfoque multidisciplinar.(AU)

Objetives: Description of two incidental cases of bladder paraganglioma in women and review of the published literature. Methods: A bibliographic search was carried out in Medline over the last 10 years according to the terms “urinary bladder” and “paraganglioma”. Results: Bladder paraganglioma (BP) accounts for less than 0.06% of bladder tumors and 10% of all paragangliomas. It may be sporadic or associated with hereditary predisposition syndromes such as Hereditary Paraganglioma-Pheochromocytoma Syndrome. Due to its rarity, there are no recommendations for treatment and monitoring but, their risk of malignancy forces a long-term follow up. The study of germinal mutations through massive sequencing ruled out the association with a hereditary syndrome. Initial management included early reassessment by cystoscopy, transurethral bladder resection (TURB) and imaging. Conclusiones: Bladder paragangliomas are rare tumors that can be associated to hereditary syndromes. Itstreatment and follow – up must be based on a multidisciplinary approach.(AU)