A new mutation in the PDE6C gene in achromatopsia

To report a case of achromatopsia with a new mutation in the PDE6C gene which has not been previously described.

Case report.

A single patient.

A 35-year-old woman with poor vision and impaired color vision. Fundus examination of both eyes (OU) revealed small optic discs. Optical coherence tomography (OCT) showed photoreceptor segment defects and a disruption of the ellipsoid layer in the foveal region, with intact overlying outer limiting membrane and underlying RPE bands. The electroretinogram (ERG) showed scotopic responses: DA 0.01: normal amplitude, b-wave latency at upper limit of normal / slightly increased. DA 3 and DA 10: slightly increased b-wave latency, asymmetry in b amplitude, being lower in the left eye. Oscillatory potentials: no responses are obtained. Photopic responses: LA-3: greatly increased latencies, decreased amplitude. Subsequently, a case of incomplete achromatopsia was suspected. Therefore, a genetic study was carried out showing the homozygous presence of the undescribed pathogenic variant c.660_661del (p.Ser221Tyrfs * 15) in exon 3 of the PDE6C gene.

Achromatopsia is an autosomal-recessive genetic disease characterized by decreased visual acuity, color blindness, photophobia, and nystagmus. Due to the variability of genetic mutations in achromatopsia, genetic characterization is mandatory in order to improve the efficiency in molecular diagnosis. This data may be useful in future therapeutic strategies. We present a previously undescribed mutation in the PDE6C gene in a patient with incomplete achromatopsia.