Characteristics of the test: (includes 1 exon per 1 gene)

LTBP2 (OMIM #602091) – p.R299X

Basic characteristics of the clinical phenotype

Mutations in the LTBP2 gene (OMIM #602091) are responsible for an autosomal recessive form of congenital glaucoma.

Glaucoma includes a group of diseases in which there is a persistently elevated intraocular pressure (IOP), which irreversibly damages the optic nerve and leads to progressive damage to central and peripheral vision. Left untreated, glaucoma leads to complete loss of visual function and absolute blindness. Glaucoma in children is divided into congenital and secondary.

Congenital glaucoma (PCG, OMIM #231300) is a disease in which intraocular pressure is permanently elevated from birth due to impaired outflow of intraocular fluid. The incidence of congenital glaucoma varies between 1:1250 to 1:20000 depending on geographic location and ethnic group.

The disease is most common in the Slovak Roma population (1:1250), followed by Saudi Arabia (1:2500), South India (1:3300) and Western nations (1:5000-22000). Congenital glaucoma is the most common cause of total blindness in children.

The p.R299X mutation in LTBP2 is found at high frequency in patients with autosomal recessive congenital glaucoma in whom mutations in the CYP1B1 gene are excluded.

Reasons for referring:

Candidates for this test are all patients with symptoms of primary congenital, juvenile, open- and closed-angle glaucoma, as well as relatives of patients in whom the mutation is known; patients in whom mutations in the CYP1B1 gene have been excluded.

Interpretation of results::

· Establishing the p.R299X point mutation in the LTBP2 gene will allow the genetic diagnosis of an autosomal recessive form of congenital glaucoma.
· The genetic counselor will interpret and answer all questions about your result.

Method: Sanger sequencing.

The method involves bidirectional DNA sequencing of exon 4 of the LTBP2 gene, where the p.R299X mutation is located. The laboratory offers sequencing of the p.R299X mutation in relatives of patients to determine the carrier status (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.