Novel KDM6A Kabuki Syndrome Mutation With Hyperinsulinemic Hypoglycemia and Pulmonary Hypertension Requiring ECMO.

Kabuki syndrome (KS) is a multisystem disorder estimated to occur in 1:32 000 newborns. Pathogenic mutations cause the majority but not all cases of KS in either KMT2D or KDM6A. KS can be suspected by phenotypic features, including infantile hypotonia, developmental delay, dysmorphic features, congenital heart defects, and others. Still, many of these features are not readily apparent in a newborn. Although neonatal hypoglycemia has been reported in 8% to 10% of patients with KS, the incidence and severity of hyperinsulinemic hypoglycemia (HH) is not well-studied. We present a full-term female infant with HH who was responsive to low-dose diazoxide. At 3 months of age, she was admitted for septic shock, worsening respiratory status, and severe pulmonary hypertension, requiring extracorporeal membrane oxygenation support. Her neonatal history was notable for hypotonia, dysphagia with aspiration requiring gastrostomy tube placement, and a cardiac defect-hypoplastic aortic arch requiring aortic arch repair. She has characteristic facial features, including prominent eyelashes, long palpebral fissures, and a short nasal columella. Next-generation sequencing for HH revealed a de novo likely pathogenic missense variant in KDM6A gene: c.3479G > T, p.Gly1160Val that was absent from population databases. Genetic testing for causes of HH should include testing of the KS genes KMT2D and KDM6A. Early detection of the underlying genetic defect will help guide management as all reported HH cases associated with KS have been responsive to diazoxide. Affected infants with underlying cardiac conditions may be at higher risk of serious respiratory complications such as pulmonary hypertension.

Neonatal Diabetes Mellitus: An Update on Diagnosis and Management.

Neonatal diabetes mellitus is likely to be due to an underlying monogenic defect when it occurs at less than 6 months of age. Early recognition and urgent genetic testing are important for predicting the clinical course and raising awareness of possible additional features. Early treatment of sulfonylurea-responsive types of neonatal diabetes may improve neurologic outcomes. It is important to distinguish neonatal diabetes mellitus from other causes of hyperglycemia in newborns. Other causes include infection, stress, inadequate pancreatic insulin production in preterm infants, among others. This review explores the diagnostic approach, mutation types, management, and clinical course of neonatal diabetes.