SP1 and hypospadias: No significant differences were found in the CpG methylation level of the promoter region of the SRD5A2 gene from − 365 to + 1 (total of 19 CpGs), the − 254 XRE site (CACGC), and the − 221 and − 72 Sp1 sites (GGGCGG) between the hypospadias and phimosis samples (Fig. 4a–d).