Characteristics of the test: (includes 1 gene)
ABCA4 (OMIM #601691)

Basic characteristics of the clinical phenotype:

Cone-rod retinal dystrophy (COD/CORD) is a rare hereditary disease with an incidence of approximately 1:40,000 worldwide. In cone dystrophies (COD), the functional deficit is limited to the daytime vision system (the cones). In other forms of cone dystrophies (probably the majority), symptoms of rod dystrophy (CORD) also appear later in the course of the disease. COD and CORD are nonprogressive and progressive according to the course of the disease, and according to the type of inheritance they are distinguished as autosomal recessive (ar), autosomal dominant (ad) and X-linked (Xl). This type of retinal dystrophy is most often non-syndromic, but can also be part of several syndromes, such as Bardet-Beidle syndrome (BBS)

The main genes with a role in the pathogenesis of CORDs are 4 and include: CRX and GUCY2D (mutations in these lead to autosomal dominant forms of CORDs), ABCA4 (which, in addition to Stargardt disease, is also responsible for 30-60% of the cases with autosomal recessive CORDs) and RPGR (which is responsible for X-linked CORDs).
Mutations in the ABCA4 gene are also responsible for other retinopathies, such as Stargardt's Disease (STGD), Retinitis pigmentosa, RP.

Reasons for referring:
All patients with symptoms of cone-rod retinal dystrophy (COD/CORD), Stargardt disease (STGD), retinal pigment degeneration (RP) and macular degeneration (MD).

Interpretation of results:
· Identification of point mutations and small deletions/insertions in the ABCA4 gene will allow a genetic diagnosis of ABCA4-related retinopathy (CORD, MD, STGD, RP)
· 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 involves bi-directional DNA sequencing of all coding exons and intron-exon boundaries of the ABCA4 gene. The laboratory offers single exon or exon pair 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.