Characteristics of the test: (includes 4 genes and one hotspot area)

RHO (OMIM #180380)

PRPH2/RDS (OMIM #179605)

PRPF31 (OMIM #606419)

IMPDH1 (OMIM #146690)

RPGR-ORF15 (OMIM #312610)

Basic characteristics of the clinical phenotype:
Retinitis pigmentosa (RP, OMIM #268000) is a group of hereditary retinal dystrophies with a worldwide incidence of 1:4000. In this disease, initially the rods are affected, and later the cones. Clinical features associated with most cases of RP include night blindness (nyctalopia), waxy pallor of the optic disc, narrowed blood vessels, presence of pigmentary masses, followed by progressive loss of peripheral vision in daylight and eventually blindness

Non-syndromic retinal pigment degeneration is a genetically and clinically heterogeneous disease. At least four forms are known so far, depending on the mode of inheritance. This includes autosomal dominant form of RP (adRP), autosomal recessive (arRP), X-linked and digenic. Also, RP may also be inherited in a mitochondrial pattern. Patients with adRP account for about 15–25% of RP cases; arRP – 30%; X-linked RP is the rarest inherited form and is responsible for 10-20% of cases.

Among the most frequently mutated in adRP cases are the rhodopsin (RHO) and peripherin (RDS/PRPH2) genes. Searching for defects in RHO, PRPH2/RDS, PRPF31, IMPDH1 and RPGR-ORF15 in patients with autosomal dominant retinal degeneration would lead to the discovery of the molecular basis of the disease in ~50% of them. Mutations in RPGR cause approximately 80% of cases of X-linked RP. The ORF15 exon is mainly expressed in the retina, and most mutations in RPGR (60%) are found in this exon.

The rhodopsin gene (RHO) is a good candidate for screening in both arRP and congenital stationary night blindness (CSNB) patients.

Reasons for referring:
All patients with symptoms of autosomal dominant retinal degeneration pigment (adRP).

Interpretation of results:
· Detection of point mutations and small deletions/insertions in genes from the panel will allow a genetic diagnosis of autosomal dominant retinal pigment degeneration.

· 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 genes RHO, PRPH2/RDS, PRPF31, IMPDH1, as well as a region of RPGR-ORF15. The laboratory offers single exon sequencing in relatives of the patient 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 the  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.