NM_000051.4:c.5600A>G (p.Gln1867Arg) is a missense variant in exon 37 of ATM. It has been reported in ClinVar as a variant of uncertain significance (ClinVar ID 453589, 4 clinical laboratories).¹ This variant is present in gnomAD v4.1 at an extremely low allele frequency (AF = 1.86e-6, 3/1,613,944 alleles, 0 homozygotes) and is absent from gnomAD v2.1 and gnomAD-Canada, meeting the ATM VCEP PM2_Supporting threshold (≤0.001%).² The ATM VCEP supplementary functional data (Suppl_TableS1, PMID 40580951) classifies this variant as 'Non-functional' (combined score -2.05, Medium-high confidence), meeting PS3_Supporting per the VCEP framework for variants that fail to rescue ATM-specific functional features.³ Multiple computational predictors suggest a benign effect: REVEL score 0.088 (meeting BP4_Supporting threshold ≤0.249), BayesDel -0.34033, AlphaMissense 0.0758. SpliceAI predicts no splicing impact (max delta 0.10, meeting BP4 splicing threshold ≤0.1).⁴ No case-control studies, co-segregation data, or confirmed de novo observations have been identified for this variant. A ClinVar submission noting observation in trans with a pathogenic ATM variant in an A-T patient was not accompanied by peer-reviewed publication, precluding application of PM3.⁵ The variant has not been reported in COSMIC and is not located in a statistically significant cancer hotspot residue.