The FMR1 CGG repeat test is not a candidate prescreening tool for identifying women with a high probability of being carriers of BRCA mutations.

The identification of women with a high probability of being carriers of pathogenic BRCA mutation is not straightforward and a major improvement would be the availability of markers of mutations that could be directly evaluated in individuals asking for genetic testing. The FMR1 gene testing was recently proposed as a candidate prescreening tool because an association between BRCA pathogenic mutations and FMR1 genotypes with 'low alleles' (CGG repeat number <26) was observed. To confirm this hypothesis, we evaluated the distribution of FMR1 alleles and genotypes between BRCA mutation carriers and non-carriers in a cohort of 147 Italian women, free of cancer or affected by breast and/or ovarian cancer, who were tested for the presence of BRCA mutation in a clinical setting. The distribution of FMR1 CGG repeat numbers in the two groups was similar (lower allele median/mean were 30/27.4 and 30/27.9, respectively; Mann-Whitney test P=0.997) and no difference in the FMR1 genotype distribution was present (χ(2)=0.503, d.f.=2, P=0.78). This result is in contrast with literature data and suggests that FMR1 genetic testing is not a candidate BRCA prescreening tool.