Retinopathy and optic atrophy in a case of <i>COQ2</i>-related primary coenzyme Q₁₀ deficiency

To describe a case of primary coenzyme Q10 deficiency in a child manifesting as early-onset renal failure, retinal dystrophy, and optic atrophy leading to progressive vision loss. Clinical presentation and workup including visual fields, electroretinogram, and optical coherence tomography are presented. Genetic testing was performed. An eight-year-old female with nephropathy requiring renal transplantation subsequently developed progressive cone-rod dystrophy and optic atrophy. The patient had negative results on a targeted next-generation sequencing retinal dystrophy panel but whole-exome sequencing revealed two variants in COQ2 (likely biallelic), consistent with a diagnosis of primary coenzyme Q10 deficiency. Primary coenzyme Q10 deficiency is a rare disorder with variable systemic and ocular findings; there is also genetic heterogeneity. Genetic testing aids in the diagnosis of this condition, and variants in the COQ2 and PDSS1 genes appear to have the strongest association with ocular manifestations. Oral supplementation of coenzyme Q10 may slow progression of disease. This case highlights the utility of whole-exome sequencing in the diagnosis of a rare syndromic form of ocular disease and reports a novel phenotypic association for this condition.