Abstract
Introduction: Achromatopsia is an autosomal recessive retinal disorder with an estimated prevalence ranging from 1 in 30.000 to 50.000. The disease is caused by mutations in six different genes.
The aim of the study was to perform molecular genetic analysis in 11 unrelated probands with a clinical diagnosis of achromatopsia and to describe clinical findings in those that were found to carry biallelic pathogenic mutations. Methods: All probands and their parents underwent ophthalmic examination.
Mutation detection was performed using Sanger sequencing of CNGB3 exons 6, 7, 9-13, which have been found to harbour most diseasecausing mutations in patients with achromatopsia of European origin. Results: Three known pathogenic variants in CNGB3 were identified in 2 probands.
Proband 1 was a compound heterozygote for the c.819_826del; p.(Arg274Valfs*13) and c.1006G>T; p.(Glu336*). Proband 2 carried the c.1148del; p.(Thr383Ilefs*13) in a homozygous state.
The best corrected visual acuity in proband 1 (aged 19 years) was 0.1 in both eyes, in proband 2 (aged 8 years) 0.05 in the right eye and 0.1 in the left eye. Both individuals had nystagmus, photophobia, and absence of colour discrimination.
Fundus examination appeared normal however spectral-domain optical coherence tomography revealed subtle bilaterally symmetrical structural changes in the fovea. Conclusion: Molecular genetic analysis of Czech patients with achromatopsia was performed for the first time.
Identification of diseasecausing mutations in achromatopsia is important for establishing an early diagnosis, participation in clinical trials assessing gene therapies and may be also used for preimplantation genetic diagnosis.