The NM_000152.5:c.2799+2C>T variant alters the donor splice site of intron 19, the final intron of GAA. Of note, the first two nucleotides of intron 19 are GC, rather than the typical GT. Therefore, the variant alters GC to GT, the first two nucleotides of a canonical splice site. In fact. the computational splicing predictor SpliceAI gives a score of 0.37 for donor gain at the normal donor splice site of intron 19, suggesting that the variant may generate a stronger intron 19 donor splice site. To our knowledge, the results of studies to analyze the impact of this variant on splicing are unavailable. Because this variant may strengthen the normal splice site, PVS1 has not been applied. The variant is absent in gnomAD v2.1.1 (PM2_Supporting). To our knowledge, this variant has not been reported in the literature in individuals with Pompe disease, There is a ClinVar entry for the variant (Variant ID: 574052). In summary, this variant meets the criteria to be classified as a variant of uncertain significance for Pompe disease. GAA-specific ACMG/AMP criteria applied, as specified by the ClinGen Lysosomal Diseases VCEP (Specifications Version 2.0): PM2_Supporting.