Isolated foot anomalies, including congenital vertical talus, were shown recently to occur in heterozygous carriers of CDMP-1 (cartilage-derived morphogenetic protein-1) gene mutations. Six families with isolated congenital vertical talus with apparent autosomal dominant inheritance were ascertained. DNA was isolated from 17 affected individuals and 24 unaffected individuals from these families and subjected to mutational analysis of the CDMP-1 gene. A missense mutation was identified (1312C>T) that results in an R438C substitution in the CDMP-1 active domain. This segregated with disease in one Northeren American family. Phenotypic variability in this family includes brachydactyly type C, clinodactyly, calcaneo valgus deformity, and congenital vertical talus. Metacarpophalangeal profiles (MCPPs) confirm incomplete penetrance in one family member. Hence, CDMP-1 mutations may be found in individuals with apparently isolated CVT, although careful examination of family members may reveal additional, subtle hand and foot abnormalities. However, mutations in CDMP-1 do not appear to be a frequent cause of isolated congenital vertical talus.