Characteristics of the test: (includes 26 genes)

Basic Characteristics of the clinical phenotype
Leber congenital amaurosis (LCA, OMIM #204000) is the most severe form of inherited retinal degeneration that is usually present at birth or manifests in the first months of a child's life. LCA is clinically characterized by reduced visual function, often accompanied by nystagmus, photophobia, farsightedness (hyperopia), significantly reduced electroretinogram, and keratoconus.

The estimated incidence of LCA is 2-3/100,000 births and accounts for 10-18% of cases of congenital blindness. A milder form of hereditary retinal degeneration is generally considered juvenile retinal pigment degeneration (Retinitis pigmentosa, RP), which is a group of hereditary retinal dystrophies with a frequency of 1:4,000 worldwide. LCA and juvenile RP overlap clinically and genetically, with an intermediate phenotype corresponding to the clinic of Cone-rod retinal degeneration (CORD) or early-onset retinal degeneration. Cone-rod retinal degeneration is 10 times rarer than RP - 1:40,000.

Leber congenital amaurosis is a genetically heterogeneous disease and is most often inherited in an autosomal recessive pattern. To date, 26 genes have been identified in which mutations lead to LCA.

 
Reasons for referring:
Candidates for this test are all patients with symptoms of LCA or CORD.

Interpretation of results:
· Detection of point mutations and small deletions/insertions in genes from the panel will allow a genetic diagnosis of LCA or CORD.
· 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.

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

Sensitivity of the method: depends on the content of GC and AT, as well as the presence of segmentally duplicated genes.

What does the test involve?
· DNA isolation and sample storage.
· Parallel sequencing of 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.