Cohort of Phenotype, Genotype, and Outcome of SCN Developmental and Epileptic Encephalopathies from Southern Part of India.

The SCN encephalopathies are one of the rare early childhood intractable epileptic encephalopathies associated with pleomorphic seizures, cognitive decline, motor, and behavioral abnormalities that begin in early infancy. There is a dearth of data on phenotype and genotype of SCN encephalopathies from the Indian subcontinent, hence we are reporting clinical and molecular profile and outcome of SCN developmental and epileptic encephalopathies. This is a retrospective chart review of SCN developmental and epileptic encephalopathies in a tertiary care center, Bangalore, India between January 2015 and March 2020. All children with clinical features of SCN developmental and epileptic encephalopathies and confirmed with pathogenic variants were included. A total of 50 cases of SCN developmental and epileptic encephalopathies were analyzed, 31 of them were male and the mean age of presentation was 7.8 months. Precipitating factors for the first episode of seizure were fever and vaccination accounting for 33 and 8 children, respectively. Forty (80%) children had prolonged seizures and 15 (30%) had epileptic spasms. All children had a normal birth history and normal development before the onset of seizures, which was followed by developmental delay and regression. Thirty (60%) children had behavioral difficulties, notable hyperactivity, and autistic features. Neuroimaging and the initial electroencephalogram (EEG) were normal in all patients. The mean age of abnormal EEG was 14 months. The various subtypes of SCN variants were SCN1A in 31 children followed by SCN2A and SCN9A in eight children each and SCN1B in three children. Frameshift and nonsense mutations were associated with more severe phenotype and poor outcome compared with missense mutations. Thirty-four patients partially responded to treatment and the rest were refractory. The results of genetic testing were used to guide treatment; sodium channel blocking antiepileptic drugs were discontinued in 15 patients and sodium channel blocking agents were started in 3 patients with partial response. Three out of four children on stiripentol had a partial response. The SCN developmental and epileptic encephalopathies can present with epileptic spasms in addition to other types of seizures. Epileptic spasms are more common in nonsense and frameshift mutations. The outcome is poor in children with epileptic spasms compared with those without epileptic spasms. Genetic testing helps to select antiepileptic drugs that lead to seizure reduction.

Rare Treatable Cause of Demyelinating Leukoencephalopathy That One Cannot Afford to Miss.

Biotinidase deficiency is a treatable neurometabolic disorder. It usually presents during the first year of life with seizures, ataxia, hypotonia, vision and hearing disturbance, alopecia, and skin rashes. It can have various neuroimaging findings but demyelinating leukoencephalopathy is an unusual finding in children with biotinidase deficiency that can cause diagnostic challenge as it can radiologically mimic perinatal hypoxic-ischemic encephalopathy or other leukodystrophies. It reverses with early diagnosis and treatment with biotin supplementation and the outcome is rewarding.

Treatable Cause of Pancytopenia, Recurrent Infections and Refractory Epilepsy: Secondary to Hereditary Folate Malabsorption (HFM) Due to Novel Pathogenic Variant.

Hereditary folate malabsorption (HFM) is a rare disorder of proton-coupled folate transporter deficiency. It is characterized by macrocytic anemia, recurrent infections, and epilepsy. A five-year-old girl presented with recurrent pneumonia, diarrhea, and mouth ulcers. On examination, pallor, microcephaly with spastic quadriparesis was noted. On investigations, leukopenia and thrombocytopenia with megaloblastic bone marrow picture and low folate levels was found. HFM was diagnosed at two years of age and the child was treated with folinic acid. Her diagnosis was confirmed by whole-exome sequencing which revealed a novel pathogenic homozygous frameshift insertion variation (c.620dupG) in the exon 2 of the SLC46A1 gene which was further confirmed by Sanger sequencing. The child improved significantly except for a partial improvement in neurological symptoms.

Case Series of Early SCN1A-Related Developmental and Epileptic Encephalopathies.

Introduction: The developmental and epileptic encephalopathies (DEEs) are a heterogeneous group of rare neurodevelopmental disorders, characterized by early onset seizures that are often intractable, electroencephalographic abnormalities, developmental delay, or regression. The SCN1A pathogenic variants can present as DEE. They are characterized by early infantile seizure onset, profound intellectual disability, and a severe hyperkinetic movement disorder. Studies are lacking, hence we are reporting a case series of early SCN1A-related DEE. The objective of the study was to report clinical and molecular aspects of early SCN1A-related DEE. Materials and Methods: A retrospective chart review of children with DEEs secondary to SCN1A pathogenic variants from January 2015 to March 2020 in a tertiary care referral center from south India. Results: Out of eleven children, seven were boys. The mean age of presentation was 3.5 months. Nine children had seizures triggered by fever. All the children presented with focal and generalized seizures along with epileptic spasms. No focal neurological deficits were noted; routine testing, neuroimaging, and metabolic tests were normal in all the cases. In all the cases, hypsarrhythmia was noted on electroencephalogram (EEG). All the children had pathogenic variants in the SCN1A gene. Five children responded to steroids, one child responded to vigabatrin, and one child responded to stiripentol, but all of them had relapsed and were refractory to other antiepileptic drugs. At follow-up, all children had developmental delays and six of them had autistic features. Conclusion: Early SCN1A-related encephalopathies should be considered in the differential diagnosis of early infantile epileptic encephalopathies. Identification of this condition is important, as treatment and outcome are different from other epileptic encephalopathies.