NM_001128849.3:c.3894C>T is a synonymous variant (p.Asp1298=) in the SMARCA4 gene. Synonymous variants that do not alter splicing are typically benign.¹ This variant is present in population databases at very low frequencies: gnomAD v2.1 (12/251,084 alleles, AF=0.0048%), gnomAD v4.1 (60/1,613,590 alleles, AF=0.0037%), and gnomAD-Canada (9/18,414 alleles, AF=0.049%). Population frequency alone is insufficient to classify this variant as benign or pathogenic by allele frequency thresholds.² SpliceAI predicts no significant impact on splicing (max delta score 0.03), and the synonymous nucleotide substitution is not predicted to create or disrupt a splice site. This supports a benign interpretation under both BP4 and BP7.³ This variant has been reported in ClinVar as Likely benign by six clinical laboratories (ClinVar Variation ID: 238439). No laboratory has submitted a conflicting classification, supporting BP6.⁴ No published literature was identified that specifically describes NM_001128849.3:c.3894C>T. All PMIDs associated with ClinVar submissions refer to methodological or guideline publications that do not mention this variant. Applying generic ACMG/AMP 2015 combination rules (Richards et al., PMID:25741868): three supporting benign criteria are met (BP4, BP6, BP7) with no pathogenic criteria met. The combination of two or more supporting benign criteria is sufficient for a classification of Likely Benign.⁵