Of note, few of these CpGs involved several hearing loss genes, including CDH23, PCDH15, or ADGRV1, that encode for stereocilia link proteins [37]; however, the study was performed in a small group of sporadic patients with MD and further studies in familial cases are needed to clarify the role of methylated CpGs in these genes. The gene discussed is PCDH15; the disease is Menkes disease.