Two Novel Disease-Causing Variants in the PDE6C Gene Underlying Achromatopsia

Abstract

We report the clinical phenotype and genetic findings of two variants in PDE6C underlying achromatopsia (ACHM). Four patients with the variant c.1670G>A in exon 13 of the PDE6C gene were identified. Additionally, one had compound heterozygous genotype, with two variants in the PDE6C gene, a variant of c.2192G>A in exon 18 and c.1670G>A in exon 13. All patients presented the symptomatic triad of decreased visual acuity, severe photophobia, and colour vision disturbances. SD-OCT showed an absence of the ellipsoid zone, creating an optically empty cavity at the fovea in three patients. The patient with the compound heterozygous genotype presented a more severe subfoveal outer retina atrophy. ERG recordings showed extinguished responses under photopic and 30-Hz flicker stimulation, with a normal rod response. We identified two new variants in the PDE6C gene that leads to ACHM.

Keywords

• pde6c gene
• achromatopsia
• multimodal imaging