Introduction: Myofibrillar myopathy (MFM) is a rare human disease, characterized by a distinct histopathological pattern of myofibrillar degeneration and protein aggregates. LDB3 protein encoded by this gene is a key Z-disk protein that interacts with α-actinin and protein kinase C.

Case Presentation: In this paper, we identified the novel heterozygous, and hence, dominant mutation in the LIM domain-binding protein 3 gene (LDB3) in a patient affected by myofibrillar myopathy (MFM). We performed direct sequencing in an Iranian patient with autosomal-dominant inheritance of MFM characterized by clinical features, and we identified a heterozygous missense mutation in exon 10, c.1687A > G (p.Ile563Val) in the LDB3 gene on chromosome 10:88476524.

Conclusions: Bioinformatics analyses using SIFT, Mutation Taster and Polyphen-2 indicated that p.Ile563Val was predicted to be damaging, disease causing, and probably damaging to and causing LDB3 dysfunction. As such, this mutation produces novel protein coding transcripts, which might explain the MFM phenotype in the patient.