PTPRN and diabetes mellitus: In this study, we retrospectively analyzed the clinical data of 12 patients with MD with a maximum follow-up of 16 years and concluded that MD has the following clinical features: early age of onset, thin or normal body size, family history of maternal-inherited diabetes or hearing loss, and negative for islet-related antibodies (ICA, GAD, IA2), which is consistent with the literature (6).