NM_001001890.2:c.30C>T (p.Ser10=) is a synonymous variant in exon 1 of RUNX1. SpliceAI predicts no significant splicing impact (max delta 0.03), supporting BP4 and BP7 at the supporting benign level per the RUNX1 MM-VCEP v3.1.0.¹ In gnomAD v4.1, c.30C>T is observed at an extremely low frequency (1/1,598,264 alleles; AF=6.26e-7), well below the VCEP PM2_Supporting threshold of ≤0.00005. All subpopulations satisfy the threshold, and the variant is absent from gnomAD v2.1.² ClinVar reports c.30C>T as Likely Benign, with expert panel review status from the ClinGen Myeloid Malignancy Variant Curation Expert Panel. No contradictory evidence supporting pathogenicity was identified in verified publications.³ No functional studies, de novo occurrences, proband case data, or segregation evidence for c.30C>T were identified in any verified publication. All ClinVar-linked PMIDs are about unrelated topics (newborn screening policy statements) and do not mention RUNX1 or this variant. Applying the RUNX1 MM-VCEP v3.1.0 point-based classification framework (Tavtigian et al. 2020): PM2_Supporting (+1), BP4 (-1), BP7 (-1). Total score: -1. This falls in the Likely Benign range (-6 to -1).⁴