The variant NM_001100.3:c.1054T>C in ACTA1 is a missense variant predicted to cause substitution of serine by proline at amino acid 352 (p.Ser352Pro). The variant is absent from gnomAD v4.1.0 (PM2_Supporting). The REVEL computational prediction analysis tool produced a score of 0.942, 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). There is no published data on this variant, however Invitae has reported the variant in three unrelated probands, two of which presented with hypotonia (PS4_Supporting; SCV000638354.5). In addition, one of these probands had a de novo occurrence of the variant with parental relationships unconfirmed (PM6). In summary, the variant meets the criteria to be classified as likely pathogenic for autosomal dominant alpha-actinopathy. ACMG/AMP criteria met, as specified by the congenital myopathies VCEP: PM2_Supporting, PP2, PP3, PS4_Supporting, PM6 (ClinGen Congenital Myopathies VCEP specifications version 2; 08/27/2024).