en Molecular Genetics & Genomics Molecular Genetics & Genomics مقاله موردی Case Report <strong>Background:</strong> The clinical phenotyping of patients with achromatopsia harboring variants in phosphordiesterase 6C (<em>PDE6C</em>) has poorly been described in the literature. <em>PDE6C</em> encodes the catalytic subunit of the cone phosphodiesterase, which hydrolyzes the cyclic guanosine monophosphate that proceeds with the hyperpolarization of photoreceptor cell membranes, as the final step of the phototransduction cascade. <strong>Methods:</strong> In the current study, two patients from a consanguineous family underwent full ophthalmologic examination and molecular investigations including WES. The impact of the variant on the functionality of the protein has been analyzed using <em>in silico</em> molecular modeling. <strong>R</strong><strong>esults:</strong> The patients identified with achromatopsia segregated a homozygous missense variant (c.C1775A:p.A592D) in <em>PDE6C</em> gene located on chromosome 10q23. Molecular modeling demonstrated that the variant would cause a protein conformational change and result in reduced phosphodiesterase activity. <strong>Conclusion:</strong> Our data extended the phenotypic spectrum of retinal disorders caused by <em>PDE6C</em> variants and provided new clinical and genetic information on achromatopsia. Achromatopsia, PDE6C, Whole exome sequencing 257 263 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-809&slc_lang=en&sid=1 Ata Bushehri 0000-0001-5327-7327 No Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran Davood Zare-Abdollahi 0000-0001-6468-5932 No Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran Hesam Hashemian 0000-0003-0836-8937 No Department of Ophthalmology, Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran Ladan Safavizadeh 0000-0001-7409-751X No Department of Opthomology, Ophthalmic Research Centre, Shahid Beheshti University (M.C.), Tehran, Iran Jalil Effati 0000-0003-4961-7186 No Meybod Genetic Research Center, Yazd, Iran Hamid Reza Khorram Khorshid 0000-0001-5112-1302 Yes Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran