tokens: However , only one ( 1 . 15 % ; 95 % confidence interval , 0 - 3 . 6 % ) of the patients was heterozygous for the BRCA1 mutant allele , and only two were heterozygous for the BRCA2 mutation ( 2 . 4 % ; 95 % confidence interval , 0 - 6 . 2 % ) .