Potocki-Lupski syndrome (PTLS) is a rare chromosomal microduplication syndrome resulting in multiple congenital abnormalities including developmental delays, autistic features, and certain structural anomalies, with cardiovascular being the most common. The phenotype of this contiguous gene duplication syndrome is quite variable and may include musculoskeletal abnormalities. Given the infrequency and novelty of this disorder, full phenotypic characterization of PTLS has not yet been fully elucidated. We present a case of severe bilateral clubfoot in a patient with PTLS. Diagnosis was made by array-based comparative genomic hybridization and confirmed by fluorescence in-situ hybridization. Because clubfoot was also present in an apparently unaffected brother, the presence of PTLS may have acted as a modifier of the phenotype. This report highlights the complex interaction of chromosomal and familial factors that contribute to musculoskeletal birth defects.