Brachydactyly type C is a limb malformation characterized by shortening of the second, third, and fifth middle and/or proximal phalanges, but it has variable phenotypic expressivity. Mutations in the growth differentiation factor-5 (GDF5) gene cause isolated brachydactyly C. Herein, we report a familial case with isolated brachydactyly type C characterized by brachymesophalangy of both second and third digits, with a GDF5 missense mutation, and discuss the phenotypic variability of the condition. Identifying more cases with genetic confirmation will help elucidate the clinical and genetic characteristics of this condition in the Korean population.