Retinitis pigmentosa with optic neuropathy and COQ2 mutations: A case report

PURPOSE: To report the clinical findings of a Japanese patient presenting with retinitis pigmentosa (RP) together with optic neuropathy and COQ2 mutations. OBSERVATIONS: The patient had experienced night blindness and photophobia since his 20s. At 27 years of age, he experienced sudden vision loss in his left eye. We performed comprehensive ophthalmic examinations. Trio-based whole-exome sequencing was performed to identify the candidate variants, which were confirmed by Sanger sequencing. Fundus examination revealed typical RP findings with an additional Leber hereditary optic neuropathy (LHON). The patient's visual acuity was severely affected, and the visual field showed central scotoma. Electroretinograms were non-recordable under scotopic condition and showed reduced response under photopic conditions. Genetic analysis revealed compound heterozygous COQ2 variants in the patient: c.469C > T [p.(P157S], and c.518G > A [p.(R173H)]. Co-segregation analysis in the unaffected parents confirmed that the two variants were in trans. During the 4-year follow-up period, his visual acuity and central scotoma gradually improved. CONCLUSION: This is the first description of a case of RP together with LHON harboring COQ2 mutations. Additional cases are necessary to more accurately determine the clinical course and mutation spectrum in this condition.