Characteristics of the test: (includes 341 genes)

Basic characteristics of the clinical phenotype:
Hereditary retinal degenerations account for half of the cases in which patients suffer from impaired vision, with an estimated incidence of 1:3000 in the general population or 1.8 million affected worldwide.

Retinal degenerations are clinically classified according to whether they are stationary or progressive and according to which photoreceptor system—rods or cones—is initially affected. Defects initially affecting the rods (eg, retinal pigment degeneration, Retinitis pigmentosa) lead to night blindness, progressing to loss of the peripheral visual field, and central vision is preserved until almost the last stage of the disease. These defects are defined as peripheral dystrophies. Peripheral dystrophies usually have a better prognosis and are less progressive.

In contrast, diseases affecting the cone system are initially characterized by loss of central and color vision (in Cone Dystrophies, COD), with almost no peripheral vision being affected unless the rods also degenerate, then the condition described such as cone-rod dystrophy (CORD). Because the normal function of the cones is impaired, patients initially report photophobia. Cone photoreceptors lose their ability to adapt to bright light and become photosensitized. Nyctalopia and central scotoma or partial/complete pericentral annular scotoma are seen in those affected. Some diseases affect both photoreceptor systems in the area of ​​the macula, but the peripheral rods and cones remain intact – these defects are known as macular dystrophies (MD). The heterogeneous clinical picture of macular dystrophies includes progressive loss of visual acuity, impaired color vision, and central scotoma.

Hereditary retinal degenerations are usually monogenic forms of progressive photoreceptor degeneration, but cases of digenic inheritance are also known. Pathogenic mutations can be autosomal recessive, autosomal dominant, and X-linked. Mutations in some genes can be both dominant and recessive (eg the RHO gene).
Retinal pigmentary degeneration (Retinitis pigmentosa OMIM #268000) is the most common form of inherited retinopathies.

Interpretation of results:
· The detection of point mutations and small deletions/insertions in the genes of the panel will allow a genetic diagnosis of retinal degeneration and refine the type of retinopathy.
· Presence of large deletions and insertions cannot be detected by this method. A combination with a suitable CNV analysis (MLPA, aCGH) is recommended for their detection.
· The genetic counselor will interpret and answer all questions about your result.

Method: Next-generation sequencing.
The method involves bi-directional DNA sequencing of all coding exons and intron-exon boundaries of the target genes. The laboratory offers Sanger sequencing of a single exon or a pair of exons in the patient's relatives to determine the carrier status in cases where the mutation is known (Test #182).

Sensitivity of the method: depends on the content of G-C and A-T, as well as the presence of segmentally duplicated genes.

What does the test involve?
· DNA isolation and sample storage.
· Parallel sequencing of the target genes.
· Bioinformatic analysis of sequencing data. For each patient, only data for the gene(s) of interest were analyzed.
· Forming a written result of the genetic test.
· Diagnostic interpretation of results and genetic counseling.

Biological material: Venous blood or DNA
For more information, please read the "Biological material requirements and shipping information" carefully.