Interestingly, many of the phototransduction genes downregulated in Mef2d−/− retinas are also mutated in human retinal diseases that result in photoreceptor degeneration, including retinitis pigmentosa (RP) and cone-rod dystrophy.14 Moreover, a decrease in MEF2 has been observed in other genetic mouse models of RP and LCA, suggesting the potential role of MEF2 transcription factors in human homologues of the disease.12,13. The gene discussed is MEF2A; the disease is cone-rod dystrophy.