Characteristics of the test: (includes 341 genes)

Basic characteristics of the clinical phenotype:

Usher syndrome is an autosomal recessive disorder characterized by hearing impairment, progressive retinal degeneration and, in some cases, vestibular dysfunction. This syndrome is the most common cause of simultaneous hearing and vision loss, accounting for over 50% of patients, affecting between 1:12,000 and 1:30,000 individuals for different populations worldwide. Three forms of Usher syndrome are known, and the clinical picture is distinguished based on the onset of the disease, severity of symptoms and involvement of the vestibular apparatus.

Usher syndrome type 2 (USH2 OMIM #276901) is characterized by moderate to severe congenital hearing loss, retinal degeneration (RD) with teenage onset, and normal vestibular function. The clinical feature of RP includes night blindness progressing to narrowing of the peripheral visual field with eventual loss of central vision, an abnormal fundus with pigment deposits and narrowed retinal vessels, and an electroretinogram (ERG) ordered.

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.