Purpose: Congenital idiopathic clubfoot is the most common musculoskeletal birth defect developing during the fetal period, but with no known etiology. MYH 2, 3, 7, and 8 are expressed embryonically or perinatally, the period during which congenital idiopathic clubfoot develops; are all components of Type II muscle, which is consistently decreased in clubfoot patients; and are associated with several muscle contracture syndromes that have associated clubfoot deformities. In this study, we hypothesized that mutations in embryonic and perinatal myosin genes could be associated with congenital idiopathic clubfoot.

Methods: We screened the exons, splice sites, and predicted promoters of 24 bilateral congenital idiopathic clubfoot patients and 24 matched controls in MYH 1, 2, 3, and 8 via sequence-based analysis, and screened an additional 76 patients in each discovered SNP.

Results: While many SNPs were found, none proved to be significantly associated with the phenotype of congenital idiopathic clubfoot. Also, no known mutations that cause distal arthrogryposis syndromes were found in the congenital idiopathic clubfoot patients.

Conclusion: These findings demonstrate that congenital idiopathic clubfoot has a different pathophysiology than the clubfoot seen in distal arthrogryposis syndromes, and defects in myosin are most likely not directly responsible for the development of congenital clubfoot. Given the complexity of early myogenesis, many regulatory candidate genes remain that could cause defects in the hypaxial musculature that is invariably observed in congenital idiopathic clubfoot.

Significance: This study further differentiates congenital idiopathic clubfoot as distinct from other complex genetic syndromes that can present with similar deformities, and thus facilitates further research to improve the clinical diagnosis and treatment of congenital idiopathic clubfoot.