The NM_000152.5:c.1961C>A (p.Ser654Ter) variant in GAA is a nonsense variant predicted to cause a premature stop codon in biologically-relevant-exon 14/20, leading to nonsense mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1). The variant is absent in gnomAD v2.1.1. (PM2_Supporting). To our knowledge, this variant has not been reported in the literature in any individual with Pompe disease. However, there is a ClinVar entry for this variant (Variation ID 372968). The classification of this variant has been upgraded from Variant of Uncertain Significance to Likely Pathogenic based on the recommendations of the ClinGen Sequence Variant Interpretation Working Group, that a variant meeting PVS1 and PM2_Supporting is classified as Likely Pathogenic (https://clinicalgenome.org/site/assets/files/5182/pm2_-_svi_recommendation_-_approved_sept2020.pdf ). In summary, this variant meets the criteria to be classified as Likely Pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria met, based on the specifications of the ClinGen Lysosomal Diseases VCEP (Specifications Version 2.0): PVS1, PM2_Supporting. (Classification approved by the ClinGen Lysosomal Diseases VCEP, March 10, 2023).