Metabolic etiologies in children with infantile epileptic spasm syndrome: Experience at a tertiary pediatric neurology center.

• Inborn errors of metabolism were identified in 5.4 % of 112 infants with IESS. • Six children were diagnosed with inborn errors of metabolism. • A case was diagnosed with congenital disorder of glycosylation type IIM and IESS with a novel de novo hemizygous missense variant in the SLC35A2. • The higher frequency of inborn errors of metabolism in our study may be related to the higher frequency of consanguineous marriages in Turkey. Infantile epileptic spasm syndrome (IESS), including West syndrome (WS) and infantile spasm (IS), causes a challenging prognosis, particularly when associated with metabolic etiologies. This study, conducted at a tertiary pediatric neurology center, explored the prevalence and clinical features of inborn errors of metabolism in 112 children with IESS over 10 years. Most patients presented with seizures, primarily flexor spasms, and the median age at onset was 5 months. Comprehensive clinical evaluation and neuroimaging revealed structural-acquired causes as the most common etiology. Notably, inborn errors of metabolism were identified in 5.4 % of cases, with six distinct diagnoses including nonketotic hyperglycinemia, pyridoxine-dependent epilepsy, primary coenzyme Q10 deficiency 7, congenital disorder of glycosylation type IIM, 6-pyruvoyl tetrahydrobiopterin synthase deficiency, and argininosuccinate lyase deficiency. The prevalence of inborn errors of metabolism in this cohort was consistent with global variations reported in the literature. Genetic testing, including karyotype analysis and whole exome sequencing, was performed in a subset of cases with no clear diagnosis, revealing abnormalities in approximately 50 % of cases. Adrenocorticotropic hormone emerged as the most frequently prescribed antiseizure medication. This study provides insight into the diagnostic challenges associated with IESS and highlights the importance of metabolic investigations, especially in cases without a clear etiology. The findings emphasize the need for further genetic and metabolic studies to enhance prognostic accuracy and guide potential treatment options for children with IESS, particularly in populations with high rates of consanguinity. [ABSTRACT FROM AUTHOR]