Abstract B10: Development of high-throughput screening methods for detecting germline cancer causing mutations in the Hispanic population
Authors: Sahasrabudhe Ruta , Tuazon Anna-Marie , Lott Paul , Estrada Ana , Bohorquez Mabel , Prieto Rodrigo , Criollo Angel , Ramirez Carolina , Echeverry Magdalena , Carvajal-Carmona Luis G. 
Published: May 2015

Colorectal and breast cancers are leading causes of cancer morbidity and mortality in Hispanics. Most of the genes predisposing to these common malignancies are yet to be identified. Moreover, the prevalence of mutations in known cancer genes in Hispanic populations remains largely undetermined. Our present study aims to establish the prevalence of mutations that predispose to cancer susceptibility syndromes in Hispanics using a high throughput next-generation sequencing approach. We have developed an amplicon sequencing method that uses microfluidics PCR to simultaneously identify mutations in up to 480 amplicons. This amount of sequence data is enough to cover, at a high depth, the coding sequence of ∼20 different genes in a single reaction. To do so, the samples are barcoded individually using indexing adapters that allows pooling of multiple amplicon libraries for up to 384 samples in a single MiSeq run. The sequence data is analyzed with a locally developed bioinformatics pipeline that uses BWA, VarScan V2.0 and custom shell and Perl scripts. Our preliminary data, in several hundred familial and early-onset colon and breast cancer patients from South America, have identified many individuals with mutations in known cancer genes, such as APC, MSH2, MLH1, BRCA1 and BRCA2, and that have been previously reported in Southern European populations. We have also identified several mutations that have not been reported previously and that appear to have an Amerindian origin. Interestingly, a large fraction of these mutations are shared by multiple patients and suggest that founder effects are common in some of these populations. We have also found that more than over 50% of the patients screened so far are mutation negative. We plan to use this latter set of samples for novel gene discovery by whole exome or genome sequencing in the next phase of our study. In conclusion, we have developed a rapid, cost effective, and efficient method for screening mutations in known cancer genes in the Hispanic population. Hispanics are the youngest, largest and the fastest growing US minority and the largest population group living in the Americas. However, to a large extent, this population remains under-studied and under-screened, contributing to health care disparities. Prevalence of mutations in known cancer genes as well as novel mutations identified in our study can be used during initial steps of genetic testing programs that can improve the detection of early cancers among Hispanic communities.

Citation Format: Ruta Sahasrabudhe, Anna-Marie Tuazon, Paul Lott, Ana Estrada, Mabel Bohorquez, Rodrigo Prieto, Angel Criollo, Carolina Ramirez, Magdalena Echeverry, Luis G. Carvajal-Carmona. Development of high-throughput screening methods for detecting germline cancer causing mutations in the Hispanic population. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B10. doi:10.1158/1538-7755.DISP13-B10