The NM_000152.5:c.1710C>G (p.Asn570Lys) variant in GAA has a minor allele frequency in gnomAD of 0.0001149 in the African population, which is lower than the ClinGen LSD VCEP threshold (<0.001) for PM2_Supporting, meeting this criterion. At least three individuals have been reported with this variant and documented GAA activity in the affected range and/or were reported to be on enzyme replacement therapy for Pompe disease (PMID: 17151339, 22538254, 29122469, 32248831) (PP4_Moderate). This variant was found in compound heterozygosity with another variant in GAA that has been classified as pathogenic by the ClinGen Lysosomal Diseases VCEP including c.2560C>T (p.Arg854Ter) (ClinVar Variation ID: 4034, SCV001371731.1), phase unconfirmed, in at least one patient with Pompe disease (PMID: 22538254, 22658377, 29122469, 31193175)(0.5 points), and confirmed in trans in a patient with c.953T>C (p.Met318Thr) (ClinVar Variation ID: 4021; SCV002583364.1) (PMID: 36636589) (1 point). Another patient with the variant, along with with c.-32-13T>G and a rare synonymous variant c.1923G>A (p.Leu641=) has been reported (PMID: 32248831). While the allelic data from the latter patient is likely supportive of pathogenicity for c.1710C>G (p.Asn570Lys), it is not included here because the impact of p.Leu641= is unknown (Total 1.5 points) (PM3). Functional assays support a deleterious effect of this variant. When expressed in COS cells, this variant was classified as Class B ("potentially less severe") by Kroos et al, 2012 (PMID:22644586). This includes 0.9% GAA activity in cells and 0.5% in medium, and evidence of abnormal synthesis and processing on Western blot (PS3_Moderate). Computational evidence is inconclusive, REVEL score = 0.662 which is lower than the LD VCEP threshold for PP3 (>0.7) but higher than the LD VCEP threshold for BP4 (<0.5), and therefore does not meet either criterion. There is a ClinVar entry for this variant (Variation ID: 555153). In summary, this variant meets the criteria to be classified as Likely Pathogenic for Pompe disease based on the specifications of the ClinGen Lysosomal Diseases Variant Curation Expert Panel. GAA-specific GAA-specific ACMG/AMP criteria met (Specifications Version 2.0): PS3_Moderate, PM3, PP4_Moderate, PM2_Supporting. (Classification approved by the ClinGen Lysosomal Diseases Variant Curation Expert Panel on November 22, 2024).