Negative correlations were found between the methylation level of SRD5A2, especially at the − 221 Sp1 site, and the CYP1 family mRNA expression levels (CYP1A1, p = 0.002; CYP1B1, p = 0.007) in hypospadias patients, but not in phimosis patients. The gene discussed is CYP1B1; the disease is hypospadias.