The c.304G>A (NM_001100.4(ACTA1):c.304G>A (p.Glu102Lys)) variant in ACTA1 is a missense variant predicted to cause substitution of glutamate by lysine at amino acid 102 (p.Glu102Lys). This variant is absent from gnomAD v4.1.0 (PM2_Supporting). ACTA1, in which the variant was identified, is defined by the ClinGen Congenital Myopathies VCEP as a gene that has a low rate of benign missense variation and where pathogenic missense variants are a common mechanism of disease (PP2). The computational predictor REVEL gives a score of 0.854, which is above the threshold of 0.7, evidence that correlates with impact to ACTA1 function (PP3). This variant has been reported in 4 probands with alpha-actinopathy (PS4_Moderate; SCV000511956, SCV003347757; Invitae & GeneDx Internal Data). At least one patient with this variant displayed muscle biopsy with fiber type disproportion, which is highly specific for alpha-actinopathy (PP4_Moderate; SCV003347757, Invitae internal data). The variant has been reported to segregate with alpha-actinopathy in one affected daughter (PP1; SCV003347757, Invitae internal data). In summary, this variant meets the criteria to be classified as likely pathogenic for autosomal dominant alpha-actinopathy based on the ACMG/AMP criteria applied, as specified by the ClinGen Congenital Myopathies VCEP: PM2_supporting, PP2, PP3, PS4_Moderate, PP4_Moderate, PP1 (ClinGen Congenital Myopathies VCEP Specifications Version 2.0, 9/9/2024).