Loss of function mutations in VARS encoding cytoplasmic valyl-tRNA synthetase cause microcephaly, seizures, and progressive cerebral atrophy.

Progressive microcephaly and neurodegeneration are genetically heterogenous conditions, largely associated with genes that are essential for the survival of neurons. In this study, we interrogate the genetic etiology of two siblings from a non-consanguineous family with severe early onset of neurological manifestations. Whole exome sequencing identified novel compound heterozygous mutations in VARS that segregated with the proband: a missense (c.3192G>A; p.Met1064Ile) and a splice site mutation (c.1577-2A>G). The VARS gene encodes cytoplasmic valyl-tRNA synthetase (ValRS), an enzyme that is essential during eukaryotic translation. cDNA analysis on patient derived fibroblasts revealed that the splice site acceptor variant allele led to nonsense mediated decay, thus resulting in a null allele. Three-dimensional modeling of ValRS predicts that the missense mutation lies in a highly conserved region and could alter side chain packing, thus affecting tRNA binding or destabilizing the interface between the catalytic and tRNA binding domains. Further quantitation of the expression of VARS showed remarkably reduced levels of mRNA and protein in skin derived fibroblasts. Aminoacylation experiments on patient derived cells showed markedly reduced enzyme activity of ValRS suggesting the mutations to be loss of function. Bi-allelic mutations in cytoplasmic amino acyl tRNA synthetases are well-known for their role in neurodegenerative disorders, yet human disorders associated with VARS mutations have not yet been clinically well characterized. Our study describes the phenotype associated with recessive VARS mutations and further functional delineation of the pathogenicity of novel variants identified, which widens the clinical and genetic spectrum of patients with progressive microcephaly.

Amantadine for the Treatment of Refractory Absence Seizures in Children.

INTRODUCTION: Childhood epilepsy is a generalized epilepsy syndrome with a favorable response to antiepileptic drugs; however, a small percentage of typical absence seizures remain refractory to drugs. We studied the safety and efficacy of amantadine in children with refractory absence seizures. MATERIALS AND METHODS: Of 48 children with typical absence seizures attending the outpatient department of a tertiary care neurological center over a period of 3 years from July 2013 to June 2016, 4 children who were refractory to standard treatment for at least 1 year were selected and were started on amantadine 4-6 mg/kg/day, after obtaining informed consent. OBSERVATIONS: The children, aged between 7 and 14 years, had more than 10 episodes of seizures per day in spite of polytherapy with valproate, lamotrigine, clonazepam, levetiracetam, and topiramate in various combinations. Electrographically, all showed the typical generalized 3 Hz spike wave discharges activated by hyperventilation. All the children became seizure free within 1 week after starting amantadine, and there was improvement in their school performance. The children continue to remain seizure free for 6-30 months now. No significant adverse effects were observed on addition of amantadine. DISCUSSION: Amantadine can be tried as a safe add-on drug for children with absence epilepsy refractory to multiple drugs. Further multicenter trials may be needed to prove its effectiveness, as the numbers are small.

Vitamin D Deficiency in Ambulant Children on Carbamazepine or Sodium Valproate Monotherapy.

OBJECTIVE: To assess the effect of monotherapy with Carbamazepine (CBZ) and Sodium valproate (VPA) on serum 25-OH Vitamin D levels in children with epilepsy compared to controls. DESIGN: Cross-sectional study. SETTING: Outpatient department of a tertiary-care Pediatric Neurology centre, and a nearby day-care centre and school. STUDY PERIOD: June 2012 to May 2013. PARTICIPANTS: Children with epilepsy aged 2 to 13 years on monotherapy with CBZ (n=28) or VPA (n=28) for at least 6 months; 109 age-matched controls from a nearby day-care centre and school. RESULTS: The median (IQR) values of 25 (OH) vitamin D was 18.0 ng/mL (13.7-27.3), 21.35 ng/mL (16.4 -25.2) and 30.5 ng/mL (19.1-43.7) in CBZ, VPA and control group, respectively (P= 0.008). 60.7% of patients in CBZ group and 35.7 % in VPA group had low 25 (OH) D levels (%20 ng/mL) compared to 27.8% in controls (P=0.001).The serum alkaline phosphatase level was higher in children on carbamazepine therapy (P=0.001) than controls. CONCLUSION: This study identifies significant risk of vitamin D deficiency in ambulant children with epilepsy on monotherapy with CBZ or VPA.

Neurometabolic disorder with microcephaly, dystonia, and central cyanosis masquerading as cerebral palsy.

Many neurodegenerative diseases can be misdiagnosed as cerebral palsy. The correct diagnosis is reached when the condition recurs in families or when there are specific clinical signs. The clinical and imaging features of 3 children, from 2 unrelated families, presenting with global developmental delay and dystonia are described, in whom the presence of cyanosis and methemoglobinemia confirmed the diagnosis of recessive hereditary methemoglobinemia type 2. Magnetic resonance imaging showed significant cerebellar atrophy in 2 of the 3 babies. In dark-skinned children, this condition is underdiagnosed, as mild cyanosis is difficult to detect. Screening for methemoglobinemia in children with dystonia, microcephaly, and progressive cerebellar atrophy can be helpful in identifying more cases. As there is no curative treatment for this autosomal recessive condition, the exact diagnosis offers the best chance for prenatal screening, by detecting deficient NADH--cytochrome b5 reductase enzyme activity or by identifying the specific mutation in cultured amniotic fluid cells.