RESUMEN
INTRODUCTION: Activating mutation of the calcium-sensing receptor gene (CASR) reduces parathyroid hormone secretion and renal tubular reabsorption of calcium, defined as autosomal dominant hypocalcemia type 1 (ADH1). Patients with ADH1 may present with hypocalcemia-induced seizures. Calcitriol and calcium supplementation in symptomatic patients may exacerbate hypercalciuria, leading to nephrocalcinosis, nephrolithiasis, and compromised renal function. METHODS: We report on a family with seven members over three generations with ADH1 due to a novel heterozygous mutation in exon 4 of CASR: c.416T>C. RESULTS: This mutation leads to substitution of isoleucine with threonine in the ligand-binding domain of CASR. HEK293T cells transfected with wild type or mutant cDNAs demonstrated that p.Ile139Thr substitution led to increased sensitivity of the CASR to activation by extracellular calcium relative to the wild-type CASR (EC50 of 0.88 ± 0.02 m
Asunto(s)
Hipocalcemia , Nefrocalcinosis , Nefrolitiasis , Humanos , Hipocalcemia/genética , Receptores Sensibles al Calcio/genética , Calcio , Hipercalciuria/genética , Creatinina , Células HEK293 , Mutación , ConvulsionesRESUMEN
AIMS: To report a novel mutation associated with developmental delay, epilepsy, and neonatal diabetes-DEND Syndrome, responsive to a novel management combination. METHODS: We describe the investigation, treatment, and genetic diagnosis of a newborn diagnosed with DEND syndrome. RESULTS: The patient was found to be de-novo heterozygous for pathogenic KCNJ11 missense variant: c.190G > A, p. (Val64Met), associated with DEND syndrome, responsive to a combination of super high doses of sulfonylurea (SU) and oral high-dose steroids. A single case was reported so far due to this mutation, presenting with severe DEND syndrome, treated by insulin only. 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. CONCLUSIONS: We have identified a 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.