Objective: To report a novel de novo vitelliform macular dystrophy (VMD2) mutation in a patient with Best macular dystrophy. Methods: Best-corrected visual acuity, dilated fundus examination, and electro-oculography were performed in a patient with Best macular dystrophy and his parents. Both the patient and his parents also had blood samples drawn, and their DNA was analyzed by direct genomic sequencing. Results: A heterozygous VMD2 gene missense mutation in exon 2 (Thr6Ala [ACA >GCA]) was identified in the proband. This mutation was not present in his clinically unaffected parents. Conclusions: A novel de novo mutation in the VMD2 gene was found in a patient whose phenotype and electro-oculographic findings were characteristic of Best macular dystrophy, whereas both parents were phenotypically and genetically unaffected. The findings in this family document that a de novo mutation needs to be considered when an isolated family member is found to have a Best disease phenotype. Objective: To report a novel de novo vitelliform macular dystrophy (VMD2) mutation in a patient with Best macular dystrophy. Methods: Best-corrected visual acuity, dilated fundus examination, and electro-oculography were performed in a patient with Best macular dystrophy and his Both the patient and his parents also had blood samples drawn, and their DNA was analyzed by direct genomic sequencing. Results: A heterozygous VMD2 gene missense mutation in exon 2 was identified in the proband. This mutation was not present in his clinically unaffected parents. Conclusions: A novel de novo mutation in the VM was found in a patient whose phenotype and electro-oculographic findings were characteristic of the best macular dystrophy, both both parents were phenotypically and genetically unaffected. The findings in this family document that a de novo mutation needs to be considered when an isolated family member is found to have a Best disease phenotype.