In a unique service, not offered anywhere else in New Zealand, a range of genetic testing options is available using consumer-funded laboratories worldwide. Usually a saliva collection kit is used to collect a sample from which DNA can be extracted, and this sample can be sent directly to the selected gene testing laboratory.
Over 200 genes are known for the retinal dystrophies. The accumulation of a one hour genetics consultation and examination, in conjunction with the results of the Electrophysiology Investigations, usually helps limit the genes of interest.
The most commonly used test is called a microarray, which contains known mutations within the known genes for a given disorder. The results are usually available in three months. A limitation of this test type is that it can only detect these known mutations. If an individual has a unique family mutation, it may not be present on the microarray.
The gold standard for genetic diagnosis is sequencing the whole gene of interest. This is usually costlier, and when a group of genes may cause a similar clinical picture, the tests are more expensive, but also more comprehensive. The pros and cons of genetic testing, costs and limitations are discussed in detail at the genetic consultation.
Wide field retinal photo of the left eye in a patient with autosomal dominant sectoral retinitis pigmentosa due to a mutation in the Rhodopsin gene. The corresponding fundus autofluoresence image highlights the area of retina which is poorly functioning.