rare diseases

Neuronal ceroid lipofuscinosis is a group of rare heredltary diseases with an incidence rate of 0.15 in 100 000 to 9 in 100 000. The disease is caused by mutations in CLN genes, which code various proteins - lyzosomal enzymes, transmembrane lyzosomal proteins, endoplasmic reticulum proteins, potassium, chlo­ride channels in lysosomes and ATPase. Neuronal ceroid lipofuscinosis type 2 is caused by a mutation in CLN2 gene, coding tripeptidyl-peptidase 1. This mutation reduces the concentration of the enzyme resulting in accumulation of lipopigment in lysosomes.

Background. Achromatopsia (rod monochromatism, complete color blindness) is a rare inherited retinal dystrophy with a prevalence of 1/30000-50000. Characteristic clinical symptoms include color blindness, pendular nystagmus, photophobia, severely reduced visual acuity due to the absence or impairment of cone function. To date, six genes have been associated with achromatopsia: CNGB3, CNGA3, GNAT2, PDE6C, PDE6H and ATF6. Diagnosis is established based on clinical symptoms, family history and comprehensive ophthalmological evaluation.