The NM_000152.5:c.546G>C variant alters that last nucleotide of exon 2 of GAA, but does not result in an amino acid change (p.Thr182=). Study using minigene analysis showed that the variant disrupts normal splicing, resulting in skipping of exon 2, with a low proportion of normal transcripts produced (PMID: 31301153). In addition, deletion of exon 2 results in complete loss of enzyme activity when expressed in heterologous cells (PMID: 7881425, 7717400). As this variant appears to allow a low level of normal splicing to occur, PVS1 was applied at the strong level (PVS1_Strong). At least 4 late-onset Pompe Disease patient with this variant had documented GAA deficiency or activity in the affected range in any appropriate tissue (PMID: 17616415, clinical lab data) (PP4_Moderate). One patient is compound heterozygous for the variant and c.-32-13T>G that has been classified as pathogenic by the ClinGen LD VCEP, phase not confirmed (PMID: 17616415). This variant has also been detected in a Pompe disease patient who was heterozygous with c.2608C>T (p.Arg870*, Pathogenic by LD VCEP), and in 3 additional patients with homozygous (Revvity Omics and Duke lab data) (PM3_Strong). The highest population minor allele frequency in gnomAD v4.1.0 is 0.000008496 (10/1177056 alleles) in the European Non-Finnish population, which is lower than the ClinGen Lysosomal Diseases VCEP’s threshold for PM2_Supporting (<0.001), meeting this criterion (PM2_Supporting). Other variants at the same nucleotide position (c.546G>T, c.546G>A), and in the same splice region (c.546+1G>T, c.546+2T>C, c.546+5G>T, and c.546del2‐5) have been reported in individuals with Pompe disease (https://www.pompevariantdatabase.nl/). All of these variants have been shown to result in skipping of exon 2 using a minigene assay (PMID: 31301153, 39905333). c.546G>T and c.546G>A have been classified as pathogenic by the ClinGen Lysosomal Diseases VCEP (PS1_Moderate).The computational splicing predictor SpliceAI gives a score of 0.84 for donor loss, predicting that the variant disrupts the donor splice site of intron 2 of GAA. But PP3 was not applied as PVS1 was applied. There is a ClinVar entry for this variant (Variation ID: 281056; 2 star review status) with 4 submitters classifying the variant as pathogenic, and 4 submitters classifying it as likely pathogenic. In summary, this variant meets the criteria to be classified as pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria applied, based in the specification of the ClinGen Lysosomal Diseases VCEP: PVS1_Strong, PS1_Moderate, PM3_Strong, PP4_Moderate, PM2_Supporting. (Classification approved by the ClinGen Lysosomal Diseases Variant Curation Expert Panel on April 1, 2025)