CCN4 and breast cancer: The most frequent co-mutated genes of CDH23 included ACOX2, EXPH5, FARP1, KRT85, MYO3A, SERINC1, TAS2R39, AFDN, C7 and CCN4. It was reported that variants of ACOX2 was associated with cardiovascular disease and breast cancer, and may serve as a cancer metabolism hallmark [21–23].