The variant NM_001100.4:c.442G>T in ACTA1 is a missense variant predicted to cause substitution of glycine by valine at amino acid 148 (p.Gly148Val). The variant is absent from gnomAD v4.1.0 (PM2_Supporting). The REVEL computational prediction analysis tool produced a score of 0.963, which is above the threshold necessary to apply PP3. 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). Two different missense variants, p.Gly148Ser and p.Gly148Arg (Variation IDs: 1364817 and 280732), in the same codon have been classified as likely pathogenic for alpha-actinopathy by the ClinGen Congenital Myopathies VCEP (PM5). This variant has been reported in 1 proband with alpha-actinopathy, and had a de novo occurrence of the variant with parental relationships unconfirmed (PM6; PMID: 32668698). In summary, this variant meets the criteria to be classified as likely pathogenic for AD alpha-actinopathy. ACMG/AMP criteria met, as specified by the Congenital Myopathies VCEP (Specification Version 2.0.0): PM2_Supporting, PP3, PP2, PM5, PM6 (ClinGen Congenital Myopathies VCEP specifications version 2.0.0; 3/10/2025).