A novel mutation in SETD1A is associated with early-onset epilepsy-a rare case report

SET Domain Containing 1A (SETD1A) is a histone H3K4 methyltransferase implicated in neurodevelopmental disorders. Pathogenic variants in this gene are associated with schizophrenia, intellectual disability, and epilepsy. Here, whole-exome sequencing and Sanger sequencing were performed on a 4-year-old Chinese girl with early-onset epilepsy and her unaffected parents. A novel de novo heterozygous variant in SETD1A (NM_014712.3: c.1067C > T/p.Ser356Phe) was identified in a patient presenting with focal-to-bilateral tonic-clonic seizures, beginning at 3 months of age. Neuroimaging revealed a normal brain MRI, and comprehensive neuropsychological assessment indicated preserved cognitive function. The variant was absent in 200 local controls and classified as likely pathogenic per ACMG criteria. This study may expand the mutation and phenotypic spectrum of SETD1A-related disorders, establishing the relationship between SETD1A variants and isolated early-onset epilepsy without accompanying severe neurodevelopmental deficits, highlighting the value of genetic testing in infants with unexplained epilepsy.