The ACTG1 gene encodes the cytoskeletal protein γ-actin, which functions in non‑muscle cells and is abundant in the auditory hair cells of the cochlea. Autosomal dominant missense mutations in ACTG1 are associated with DFNA20/26, a disorder that is typically characterized by post‑lingual progressive hearing loss. To date, 17 missense mutations in ACTG1 have been reported in 20 families with DFNA20/26. The present study described a small family with autosomal dominant nonsyndromic hearing loss. A novel heterozygous missense mutation, c.94C>T (p.Pro32Ser), in ACTG1 was identified using the TruSight One sequencing panel. Notably, congenital hearing loss in our proband was identified by newborn hearing screening at birth. In silico predictions of protein structure and function indicate that the p.Pro32Ser mutation may result in conformational changes in γ‑actin. The present study expands the understanding of the phenotypic effects of heterozygous missense mutations in the ACTG1 gene. In specific, the present results emphasize that mutations in ACTG1 result in a diverse spectrum of onset ages, including congenital in addition to post‑lingual onset.