NM_006015.5:c.2378_2396del (p.Met793ArgfsTer34) is a frameshift deletion predicted to undergo nonsense-mediated decay in ARID1A, a gene with an established loss-of-function disease mechanism associated with BAFopathies including Coffin-Siris syndrome. PVS1 is applied at very strong strength under the ClinGen SVI PVS1 framework (PMC6185798).¹ The variant truncates the ARID1A protein at codon 793, removing approximately 65% of the coding sequence including all C-terminal functional domains critical for SWI/SNF chromatin remodeling complex assembly and tumor suppression. PM1 is applied at moderate strength.² The variant is absent from all population databases including gnomAD v2.1, v4.1, and gnomAD-Canada. PM2 is applied at supporting strength.³ No variant-specific functional studies, clinical case reports, segregation data, de novo observations, or ClinVar classifications are available for this variant. All reviewed publications discuss ARID1A at the gene level and do not mention NM_006015.5:c.2378_2396del.⁴ Applying the ACMG/AMP 2015 combination rules: PVS1 (very strong) + PM1 (moderate) + PM2 (supporting) meets the pathogenic threshold (1 Very Strong + 1 Moderate + ≥1 Supporting). The variant is classified as Pathogenic.⁵