Utilidad del estudio genético, mediante un amplio panel de genes clínicamente accionables, en el síndrome de cáncer de mama y ovario hereditario

El SCMOH siempre ha ido vinculado a variantes patogénicas en los genes BRCA1 y BRCA2; sin embargo, hoy en día, se sabe que existen otros genes involucrados en este síndrome. En este trabajo, gracias a la técnica de secuenciación masiva de nueva generación (NGS), se ha realizado el estudio genético del SCMOH sobre una cohorte de 414 casos índices, seleccionada previamente por la consulta de asesoramiento genético de la región de Murcia según los criterios de la SEOM 2019, aplicando un panel de 50 genes, de los cuales 20 clínicamente accionables recomendados por la NCCN. En este estudio, con un rendimiento diagnóstico obtenido del 15,22%, se confirma la necesidad de incorporar en el análisis genético el panel de genes clínicamente accionables recomendado por la guía clínica NCCN, seleccionando de forma adecuada a los pacientes candidatos a estudio, a través de una consulta de asesoramiento genético en cáncer hereditario. El fenotipo de cáncer de ovario epitelial de alto grado es el que presenta un mayor rendimiento diagnóstico dentro del SCMOH, por lo que se confirma la importancia de seleccionar a este grupo de pacientes independientemente de su historia familiar. Sin embargo, el empleo de los criterios de selección individuales de la SEOM 2019, relacionados con el cáncer de mama es un factor limitante a la hora de detectar pacientes con cáncer SCMOH portadores de una VP/VPP. En este estudio, y en concordancia con lo descrito en la bibliografía, las VP/VPP detectadas en los genes BRCA presentan una mayor contribución en el SCMOH que las VP/VPP de los genes no BRCA, con un 56,9% frente al 43,1% respectivamente. No obstante, la aportación de estos últimos es considerable, destacando en nuestro estudio la elevada contribución del gen ATM, que fue superior al resto de los estudios europeos y mundiales, debido a la VP c.8251_8254del, en donde se ha demostrado previamente su efecto fundador en población murciana. Existe una asociación estadísticamente significativa entre el cáncer de mama triple negativo y el gen BRCA1, y el cáncer de mama bilateral y los genes BRCA1 y CHEK2. Con respecto a la edad media de diagnóstico de cáncer de mama unilateral, esta es más baja en aquellos pacientes portadores de una VP/VPP en BRCA2. La reevaluación de las VUS consigue disminuir de forma considerable el número de éstas, siendo recomendable que los laboratorios asistenciales utilicen esta estrategia de reevaluación periódicamente. De forma complementaria, el algoritmo de priorización de VUS permite a los laboratorios clínicos gestionar de forma más eficiente sus recursos y hacer frente al número elevado de VUS que se detectan diariamente tras el análisis de paneles de genes en la práctica asistencial. La metodología basada en la técnica RT-PCR es una herramienta fundamental en la clasificación de aquellas variantes genéticas susceptibles de generar un splicing aberrante según los programas de predicción bioinformáticos. De hecho, esta técnica ha servido para demostrar que la variante genética c.375+2T>C en el gen TP53 produce una maduración aberrante del transcrito que, en el caso de síntesis proteica, generaría una proteína truncada. En el estudio de genes candidatos para el SCMOH cabría destacar las VP obtenidas en los genes de baja penetrancia MRE11, RAD50 y XRCC2. Sin embargo, y según la evidencia actual, en estos casos sólo es posible realizar el seguimiento de los casos índices y familiares portadores de las VP/VPP detectadas. Por tanto, estos genes solo se deberían de usar para fines de investigación hasta que haya una mayor evidencia científica. Mientras tanto, en la práctica asistencial es recomendable utilizar únicamente paneles que incorporen todos los genes clínicamente accionables descritos por las sociedades científicas para cada síndrome hereditario.Hereditary breast and ovarian cancer syndrome (HBOC) has always been linked to pathogenic variants in the BRCA1 and BRCA2 genes; however, nowadays, it is known that there are other genes involved in this syndrome. In this work, thanks to the massive next-generation sequencing (NGS) technique, the genetic study of HBOC has been performed on a cohort of 414 index cases, previously selected by the genetic counseling consultation of the region of Murcia, according to the SEOM 2019 criteria, applying a panel of 50 genes, of which 20 clinically actionable recommended by the NCCN. In this study, a diagnostic yield obtained of 15.22% confirms the need to incorporate in the genetic analysis the panel of clinically actionable genes recommended by the NCCN clinical guideline, , through a genetic counseling consultation in hereditary cancer in which an appropriate selection of patients who are candidates for study is done. The high-grade epithelial ovarian cancer phenotype is the one with the highest diagnostic yield within the HBOC, thus confirming the importance of selecting this group of patients regardless of their family history. However, the use of the individual selection criteria of the SEOM 2019, related to breast cancer is a limiting factor when detecting patients with HBOC cancer carrying a VP/VPP. In this study, and in agreement with that described in the literature, the VP/VPP detected in the BRCA genes present a greater contribution in HBOC than the VP/VPP of the non-BRCA genes, with 56.9% versus 43.1%, respectively. However, the contribution of the latter is considerable, highlighting in our study the high contribution of the ATM gene, which was higher than the rest of the European and world studies, due to the VP c.8251_8254del, where its founder effect has been previously demonstrated in the Murcian population. There is a statistically significant association between triple-negative breast cancer and the BRCA1 gene, and bilateral breast cancer and the BRCA1 and CHEK2 genes. With respect to the mean age at diagnosis of unilateral breast cancer, this is lower in those patients carrying a VP/VPP in BRCA2. The re-evaluation of VUS considerably reduces the number of VUS, and it is recommended that laboratories use this re-evaluation strategy periodically. In addition, the VUS prioritization algorithm allows clinical laboratories to manage their resources more efficiently and to cope with the high number of VUS detected daily after gene panel analysis in clinical practice. The methodology based on the RT-PCR technique is a fundamental tool in the classification of those genetic variants susceptible to generate an aberrant splicing according to bioinformatics prediction programs. In fact, this technique has served to demonstrate that the genetic variant c.375+2T>C in the TP53 gene produces an aberrant maturation of the transcript that, in the case of protein synthesis, would generate a truncated protein. In the study of candidate genes for HBOC, the VP obtained in the low penetrance genes MRE11, RAD50 and XRCC2 should be highlighted. However, and according to current evidence, in these cases it is only possible to follow up index cases and family members carrying the VP/VPP detected. Therefore, these genes should only be used for research purposes until there is more scientific evidence. In the meantime, in healthcare practice it is advisable to use only panels that incorporate all the clinically actionable genes described by the scientific societies for each hereditary syndrome

Recurrent genetic variants and prioritization of variants of uncertain clinical significance associated with hereditary breast and ovarian cancer in families from the Region of Murcia

© 2023 the author(s). This manuscript version is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by/4.0/. This document is the Published version of a Published Work that appeared in final form in Advances in Laboratory Medicine. To access the final edited and published work see https://doi.org/10.1515/almed-2023-0103Objectives Hereditary breast and ovarian cancer (HBOC) follows an autosomal dominant inheritance pattern of cancer susceptibility genes. The risk of developing this disease is primarily associated with germline mutations in the BRCA1 and BRCA2 genes. The advent of massive genetic sequencing technologies has expanded the mutational spectrum of this hereditary syndrome, thereby increasing the number of variants of uncertain clinical significance (VUS) detected by genetic testing. Methods A prevalence study of HBOC was performed within 2,928 families from the Region of Murcia, in southeastern Spain. Genetic testing enabled the identification of recurrent pathogenic variants and founder mutations, which were mainly related to the BRCA1 and BRCA2 genes. VUS testing was performed using a prioritization algorithm designed by our working group. Results Variants c.68_69del, c.212+1G>A, and c.5123C>A were detected in 30 % of BRCA1 carriers, whereas exon 2 deletion concurrent with c.3264dupT, c.3455T>G and c.9117G>A variants were found in 30 % of BRCA2 carriers. A total of 16 VUS (15 %) were prioritized. Conclusions The genotype-phenotype correlation observed in our study is consistent with the scientific literature. Furthermore, the founder effect of c.1918C>T (BRCA1) and c.8251_8254del (ATM) was verified in the Murcian population, whereas exon 2 deletion (BRCA2) was proven to be a Spanish founder mutation. Our algorithm enabled us to prioritize potentially pathogenic VUS that required further testing to determine their clinical significance and potential role in HBOC

Recurrent genetic variants and prioritization of variants of uncertain clinical significance associated with hereditary breast and ovarian cancer in families from the Region of Murcia

Hereditary breast and ovarian cancer (HBOC) follows an autosomal dominant inheritance pattern of cancer susceptibility genes. The risk of developing this disease is primarily associated with germline mutations in the BRCA1 and BRCA2 genes. The advent of massive genetic sequencing technologies has expanded the mutational spectrum of this hereditary syndrome, thereby increasing the number of variants of uncertain clinical significance (VUS) detected by genetic testing

Variantes genéticas recurrentes y priorización de variantes de significado clínico desconocido asociadas al síndrome de cáncer de mama y ovario hereditario en familias de la Región de Murcia

El síndrome de cáncer de mama y ovario hereditario (SCMOH) presenta un patrón de herencia autosómica dominante en genes de susceptibilidad al cáncer y su riesgo está principalmente vinculado a mutaciones germinales en BRCA1 y BRCA2. Sin embargo, la implementación de paneles genéticos mediante secuenciación masiva en la práctica asistencial, ha ampliado el espectro mutacional de este síndrome hereditario y el número de variantes de significado clínico desconocido (VUS) detectadas en los estudios genéticos