De novo ATP1A3 variants cause polymicrogyria

Polymicrogyria is a common malformation of cortical development whose etiology remains elusive. We conducted whole-exome sequencing for 124 patients with polymicrogyria and identified de novo ATP1A3 variants in eight patients. Mutated ATP1A3 causes functional brain diseases, including alternating hemiplegia of childhood (AHC), rapid-onset dystonia parkinsonism (RDP), and cerebellar ataxia, areflexia, pes cavus, optic nerve atrophy, and sensorineural deafness (CAPOS). However, our patients showed no clinical features of AHC, RDP, or CAPOS and had a completely different phenotype: a severe form of polymicrogyria with epilepsy and developmental delay. Detected variants had different locations in ATP1A3 and different functional properties compared with AHC-, RDP-, or CAPOS-associated variants. In the developing cerebral cortex of mice, radial neuronal migration was impaired in neurons overexpressing the ATP1A3 variant of the most severe patients, suggesting that this variant is involved in cortical malformation pathogenesis. We propose a previously unidentified category of polymicrogyria associated with ATP1A3 abnormalities.

A pediatric patient with hyponatremic hypertensive syndrome without persistent hypertension in acute phase: A case report and review of literature

Hyponatremic hypertensive syndrome is characterized by hypertension, hyponatremia, and hypokalemia due to unilateral renal artery stenosis. We herein report a 1-year-old hyponatremic hypertensive syndrome infant without persistent hypertension in the acute phase. On the ninth hospital day, his systolic and diastolic blood pressure increased up to 154-160 and 70-84 mmHg, respectively. Acute gastroenteritis and dehydration might transiently mask his hypertension. By percutaneous transluminal balloon angioplasty for right renal artery, his blood pressure finally normalized without antihypertensive drugs. We reviewed 23 previously reported pediatric patients with hyponatremic hypertensive syndrome under the age of 15 years. Including our patient, there are only three reports on hyponatremic hypertensive syndrome without persistent hypertension in the acute phase. Hyponatremic hypertensive syndrome is curable with proper diagnosis and timely intervention. Therefore, pediatricians should pay attention to the signs and symptoms associated with hyponatremic hypertensive syndrome, even if persistent hypertension was absent in the acute phase.

Clinical and genetic characteristics of patients with Doose syndrome

OBJECTIVE

To elucidate the genetic background and genotype-phenotype correlations for epilepsy with myoclonic-atonic seizures, also known as myoclonic-astatic epilepsy (MAE) or Doose syndrome.

METHODS

We collected clinical information and blood samples from 29 patients with MAE. We performed whole-exome sequencing for all except one MAE case in whom custom capture sequencing identified a variant.

RESULTS

We newly identified four variants: SLC6A1 and HNRNPU missense variants and microdeletions at 2q24.2 involving SCN1A and Xp22.31 involving STS. Febrile seizures preceded epileptic or afebrile seizures in four patients, of which two patients had gene variants. Myoclonic-atonic seizures occurred at onset in four patients, of which two had variants, and during the course of disease in three patients. Variants were more commonly identified in patients with a developmental delay or intellectual disability (DD/ID), but genetic status was not associated with the severity of DD/ID. Attention-deficit/hyperactivity disorder and autistic spectrum disorder were less frequently observed in patients with variants than in those with unknown etiology.

SIGNIFICANCE

MAE patients had genetic heterogeneity, and HNRNPU and STS emerged as possible candidate causative genes. Febrile seizures prior to epileptic seizures and myoclonic-atonic seizure at onset indicate a genetic predisposition to MAE. Comorbid conditions were not related to genetic predisposition to MAE.