A homozygous variant causes recessive cone-rod dystrophy.

: To report a case of initial cone dystrophy that advanced to a cone-rod dystrophy with homozygous variants in the gene.: Retinal structure and visual function assessments were performed using fundoscopy, spectral-domain optical coherence tomography, full field electroretinography, semi-kinetic perimetry, and Ishihara plate testing. A DNA sample was collected and sent for diagnostic molecular genetic testing with a cone-rod dystrophy panel.: Clinical examination and electroretinography confirmed a clinical diagnosis of cone dystrophy. Molecular genetic testing revealed homozygous variants in (c.1355 G > A, p.(Arg452Gln)). Follow-up three years later showed progression to a cone-rod dystrophy.: Our case describes an ophthalmological phenotype associated with a homozygous missense variant and provides clinical support for variant classification.