[37] published a retrospective study focused on patients assessed in the hereditary cancer unit in Madrid; they found MUTYH variants in 56 cases (rate: 1.6%); the most frequent mutations were c.1187G>A (p.Gly396Asp), 62.9% and c.536A>G (p.Tyr179cys), 9.7%; 89.2% had heterozygous mutations, while the other 6 had homozygous MUTYH mutations (n = 2) or a monoallelic mutation in MUTYH plus a pathogenic/likely pathogenic mutation in another gene (n = 4); once again, it was concluded that there was no relationship between BC risk and monoallelic MUTYH variants based on their data. This evidence concerns the gene MUTYH and breast cancer.