The genetics of hereditary cancer risk syndromes in Brazil: a comprehensive analysis of 1682 patients

Abstract

Hereditary cancer risk syndromes are a group of disorders caused by germline variants in a growing number of genes. Most studies on hereditary cancer have been conducted in white populations. Here we report the largest study in Brazilian individuals with multiple, self-reported, ethnicities. We genotyped 1682 individuals from all regions of the country who were referred to genetic testing for hereditary cancer risk with multigene Next-generation sequencing (NGS) panels. Most were women, and had a personal and/or family history of cancer. The majority of cancer cases were breast and ovarian. We identified a total of 321 pathogenic/likely pathogenic (P/LP) variants in 305 people (18.1%), corresponding to 166 unique variants. These variants were distributed among 32 genes, and most were detected on BRCA1 and BRCA2 (129 patients, 26.2% and 14.3% of all P/LP hits, respectively). The prevalence of any genes transheterozygosity in our sample was 0.89% (15/1682). The BRCA1/BRCA2 double heterozygosity rate was 0.78% (1/129) for BRCA variants carriers and 0.06% (1/1682) overall. We classified patients according to the NCCN and Brazilian National Health Agency (ANS) genetic testing recommendation criteria. We found that the criteria had false negative rates of 17.3% and 44.2%, meaning that both failed to detect a substantial part of P/LP positive patients. Therefore, our results show that NGS adds to knowledge on the Brazilian spectrum of germline variants associated with cancer risk and indicate that Brazilian testing guidelines should be improved.

Contribution of Inherited Variants to Hereditary Cancer Syndrome Predisposition

“…Up to now, more than 200 hereditary cancer syndromes have been reported (Machačkova et syndromes and the preventive procedures can be performed to the patients. The family members that are at risk can also be tested and genetic counseling can be given to them (according to the test results) (de Oliveira et al 2022).…”