Based on the identification of sex chromosomes, candidate sex-determining genes have been identified, such as breast cancer anti-estrogen resistance protein 1 (bcar1) in I. punctatus, PDZ domain-containing gene (pfpdz1) in P. fulvidraco, anti-Müllerian hormone receptor type 2 on the Y chromosome (amhr2y) in S. meridionalis and male-specific duplication of amhr2 (amhr2by) in P. hypophthalmus [29–32]. Here, BCAR1 is linked to breast cancer.