Oculodentodigital syndrome (O.D.) is an autosomal dominant disorder comprising facial anomalies, syndactyly, microcorneae, dental enamel hypoplasia, and leukodystrophy. We describe a four generation family with O.D. in which anomalies such as syndactyly appear congenitally, whereas neurological (i.e., leukodystrophic) signs and symptoms tend to be expressed in a more severe form and/or at an earlier age of onset in successive generations of the kindred. This pattern of phenotypic expression is consistent with the phenomenon of genetic anticipation, and we suggest that O.D. may be a trinucleotide repeat disorder.