Abstract
Mutations in KCNJ11 gene cause a variety of persistent neonatal diabetes mellitus syndromes (PNDM), with and without developmental delay and epilepsy presentations (developmental delay, epilepsy, and neonatal diabetes - DEND Syndrome). We report a heterozygous mutation for pathogenic KCNJ11 missense variant: c.190G>A, p. (Val64Met), reported once so far, associated with severe epilepsy and neurological deterioration phenotype, responsive to a combination of super high doses of Glibenclamide (Sulfonylurea) and oral steroids. We had the patient attached to continuous glucose monitoring, performed electroencephalogramic tracings, magnetic resonance imaging and whole exome sequencing on parents and patient DNA and Sanger sequencing (SS) on candidate gene mutations. His phenotypic description and management during 18 months, demonstrates this mutation is responsive to super-high doses of SU combined with high dose 6 weeks steroids protocol. In conclusion, we have identified a de novo heterozygous missense mutation as the etiology for severe DEND syndrome in a one day old neonate, presenting with asymptomatic hyperglycemia, responsive to a novel management combination.