A substitution of G to C in the cone cGMP-phosphodiesterase γ subunit gene found in a distinctive form of cone dystrophy

Our results indicate that mutations in the PDE6H gene are not common, because only 1 of 240 patients with cone dystrophy showed a single nucleotide substitution in the 5′ UTR of PDE6H mRNA that could be associated with the disease. If the effect of the G to C substitution we observed in vitro also occurs in vivo, it will lead to PDE6H overexpression in the photoreceptors. Excess of PDEγ may affect normal cone cGMP-PDE function by inhibiting the catalytic PDEα,β activity and lead to pathogenic elevation of cGMP and eventual degeneration of cone photoreceptors.