Permanent neonatal diabetes mellitus: prevalence and genetic diagnosis in the SEARCH for Diabetes in Youth Study

Background Neonatal diabetes mellitus ( NDM ) is defined as diabetes with onset before 6 months of age. Nearly half of individuals with NDM are affected by permanent neonatal diabetes mellitus ( PNDM ). Mutations in KATP channel genes ( KCNJ11 , ABCC8 ) and the insulin gene ( INS ) are the most common causes of PNDM . Objective To estimate the prevalence of PNDM among SEARCH for Diabetes in Youth ( SEARCH ) study participants (2001–2008) and to identify the genetic mutations causing PNDM . Methods SEARCH is a multicenter population‐based study of diabetes in youth <20 yr of age. Participants diagnosed with diabetes before 6 months of age were invited for genetic testing for mutations in the KCNJ11 , ABCC8 , and INS genes. Results Of the 15,829 SEARCH participants with diabetes, 39 were diagnosed before 6 months of age. Thirty‐five of them had PNDM (0.22% of all diabetes cases in SEARCH ), 3 had transient neonatal diabetes that had remitted by 18 months and 1 was unknown. The majority of them (66.7%) had a clinical diagnosis of type1 diabetes by their health care provider. Population prevalence of PNDM in youth <20 yr was estimated at 1 in 252 000. Seven participants underwent genetic testing; mutations causing PNDM were identified in five (71%), (two KCNJ11 , three INS ). Conclusions We report the first population‐based frequency of PNDM in the US based on the frequency of PNDM in SEARCH . Patients with NDM are often misclassified as having type1 diabetes. Widespread education is essential to encourage appropriate genetic testing and treatment of NDM .