The c.2558G>A variant in SCN2A is a missense variant predicted to cause subsitution of arginine by glutamine at amino acid 853 (p.Arg853Gln). This variant has been identified as a de novo occurrence with confirmed parental relationships in at least 4 individual(s) identified in the published literature (PMIDs: 23935176 , 23934111, 31139143, 28708303], with additional evidence published reports available (PS2). It is absent from gnomAD v2.1.1 (PM2_Supporting). Heterologous expression assay with voltage clamping showed a decrease in peak current of 51%, which is below the threshold of 72.1%, evidence that correlates with PS3. It is a missense variant that resides within a pathogenic enriched region that is defined as a mutational hotspot (PM1). The computational predictor REVEL gives a score of 0.95, which is above the threshold of 0.773, evidence that correlates with a maximum strength of PP3_Moderate. In summary, this variant meets the criteria to be classified as PATHOGENIC for AUTOSOMAL DOMINANT COMPLEX NEURODEVELOPMENTAL DISORDER based on the ACMG/AMP criteria applied, as specified by the ClinGen Epilepsy Sodium Channel VCEP: PS2, PS3, PP3_Moderate, PM2_Supporting. (Epilepsy Sodium Channel VCEP specifications version 1.0)