International audience ; Recently, a variant allele in the 3′UTR of the gene (rs61764370 T>G) was shown to be associated with an increased risk for developing non-small cell lung cancer, as well as ovarian cancer, and was most enriched in ovarian cancer patients from hereditary breast and ovarian cancer families. This functional variant has been shown to disrupt a - miRNA binding site leading to increased expression of KRAS in vitro. In the current study, we have genotyped this -variant in breast cancer index cases from 268 families, 89 families, 685 non-/ families, and 797 geographically matched controls. The allele frequency of the -variant was found to be increased among patients with breast cancer from , but not or non-/ families as compared to controls. As carriers mostly develop ER-negative breast cancers, we also examined the variant allele frequency among indexes from non-/ families with ER-negative breast cancer. The prevalence of the -variant was, however, not significantly increased as compared to controls suggesting that the variant allele not just simply associates with ER-negative breast cancer. Subsequent expansion of the number of carriers with breast cancer by including other family members in addition to the index cases resulted in loss of significance for the association between the variant allele and mutant breast cancer. In this same cohort, the -variant did not appear to modify breast cancer risk for carriers. Importantly, results from the current study suggest that -variant frequencies might be increased among carriers, but solid proof requires confirmation in a larger cohort of carriers.