Here, we report the identification of a novel homozygous CISD2 mutation (c.215A > G; p.Asn72Ser) in a patient with a “classical” WS phenotype marked by childhood-onset insulin-dependent diabetes mellitus and progressive visual failure secondary to optic atrophy, but without peptic ulcers or defective platelet aggregation as reported previously in affected CISD2 mutation carriers. This evidence concerns the gene CISD2 and Leber hereditary optic neuropathy.