Characteristics of the test: (includes 1 gene)
RPE65 (OMIM #180069)

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 1:4000 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. Leber congenital amaurosis is a genetically heterogeneous disease and is most often inherited in an autosomal recessive pattern.

Reasons for referring:
Candidates for this test are all patients with symptoms of LCA, RP or CORD, as well as relatives of patients in whom the mutation is known.

Interpretation of results:
· Identification of point mutations and small deletions/insertions in the RPE65 gene will allow a genetic diagnosis of LCA, RP 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.

Method: Sanger sequencing.
The method includes bi-directional DNA sequencing of all coding exons and intron-exon boundaries of the RPE65 gene. The laboratory offers single exon sequencing in relatives of patients to determine the carrier status in cases where the mutation is known (Test #182).

Sensitivity of the method: 99.5%

What does the test involve?
· DNA isolation and sample storage.
· Direct sequencing of target genes/gene regions to detect pathogenic mutations.
· 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.