Identification of germline 185delAG BRCA1 mutations in non‐Jewish Americans of Spanish ancestry from the San Luis Valley, Colorado

BACKGROUND Germline mutations in the BRCA1 and BRCA2 genes are associated with an inherited predisposition to breast and ovarian carcinoma, and specific mutations in these genes are found at increased frequency in certain populations. The authors observed a repeated occurrence of the 185delAG mutation (BRCA1; also known as 187delAG) in a non‐Jewish population that originated from the San Luis Valley in Colorado. METHODS This was a retrospective analysis of mutations that occur in non‐Jewish Americans of Spanish ancestry from Colorado who were tested clinically for BRCA1 and BRCA2 genetic mutations using DNA sequencing. RESULTS Between August 1994 and December 2001, 19 Spanish/Latin American individuals from different families underwent genetic counseling and clinical genetic testing using direct DNA sequencing for mutations of the BRCA1 and BRCA2 genes. The results showed that 10 of 19 individuals had mutations or variants of BRCA1 or BRCA2, and 6 of 10 individuals (60%) carried the 185delAG mutation in BRCA1. All six families originated from the San Luis Valley in Colorado, indicated that they were of Spanish/Latin American ethnicity, and denied Jewish ancestry. CONCLUSIONS The 185delAG mutation is common in families of non‐Jewish ancestry originating from the San Luis Valley in Colorado with hereditary breast/ovarian carcinoma, possibly due to a founder effect. Further investigation may lead to simplified genetic testing and may allow clinicians to serve this population better. The repeated occurrence of the 185delAG mutation in this specific population may have clinical and public health implications. Cancer 2003;98:597–602. © 2003 American Cancer Society. DOI 10.1002/cncr.11533 Americans of Spanish ancestry from the San Luis Valley, Colorado, carry a 185delAG mutation in the BRCA1 gene that is responsible for hereditary breast and ovarian carcinomas. The prevalence of this mutation may have clinical implications for this population.