NM_177438.3:c.2997T>G (p.Leu999=) is a synonymous variant in exon 19 of DICER1. It is present at high frequency in gnomAD v4.1 with an overall allele frequency of 0.31% (5007/1613832 alleles) and 121 homozygotes. The highest subpopulation frequency is 5.69% in African/African American individuals (4272/75026 alleles, 116 homozygotes), exceeding the VCEP BA1 stand-alone benign threshold of >0.3%.¹ BA1 (Stand-Alone Benign) is met: the African/African American subpopulation allele frequency of 5.69% exceeds the 0.3% threshold with >2000 alleles tested and ≥5 alleles present. A frequency of this magnitude is incompatible with a highly penetrant autosomal dominant tumor predisposition disorder.² BS1 (Strong Benign) is independently met at the >0.03% threshold in the same subpopulation, subsumed by the stronger BA1 evidence.³ BS2_Supporting is met: 121 homozygous individuals are reported in gnomAD v4.1, satisfying the VCEP threshold of ≥2 homozygotes in individuals lacking clinical information.⁴ BP4_Supporting is met: SpliceAI predicts no splicing impact for this synonymous variant (max delta score = 0.03).⁵ BP7_Supporting is met: the variant is a synonymous change (p.Leu999=) and meets BP4, satisfying the DICER1 VCEP BP7 requirements.⁶ This variant has been classified as Benign by 10 clinical laboratories in ClinVar (VariationID: 261920), consistent with the population frequency evidence.⁷ No publications among the seven reviewed (PMID:25741868, 26467025, 24493721, 29474644, 24761742, 25394175, 28492532) specifically mention NM_177438.3:c.2997T>G or p.Leu999=. All are methodology, guideline, or gene-level review papers without variant-specific evidence.⁸ Under the Tavtigian point-based system (DICER1 VCEP v1.4.0): BA1 = -8 points. BS2_Supporting = -1 point. BP4_Supporting = -1 point. BP7_Supporting = -1 point. Total = -11 points. Classification: Benign (≤ -7).⁹