Usefulness of genetic testing for inherited retinal disease
Molecular diagnosis is useful in inherited retinal diseases (IRD) as it not only confirms the diagnosis but will also identify the correct inheritance pattern and allow accurate genetic counselling for the patient and their family. It will also inform on prognosis, which is particularly important in young subjects. In the case of infants and young children, molecular diagnosis helps to identify those children who are at risks of systemic problems such as renal disease and who will benefit from early diagnosis and treatment, precise genetic diagnosis allows preimplantation and prenatal diagnosis for those families who wish to use these services. As we advance in our knowledge of IRD, new treatments are emerging, and trials are already underway.
The main reason that patients are now requesting molecular testing is that they are increasingly becoming well informed about clinical trials of new therapies. Many of the trials involving gene therapy require knowledge of the specific genetic mutation causing the disease. Gene therapy trials are already underway for specific forms of
- Leber’s congenital amaurosis
- Retinitis pigmentosa
- Usher syndrome type 1
- Stargardt’s disease
- Juvenile X-Linked retinoschisis.
Recruitment to these trials will depend on their being sufficient numbers for these rare disorders, who know their specific disease gene mutation. Once such therapies reach the clinic, it will be even more important to identify patients who can benefit.
At the moment, unfortunately, insurance companies and other agencies funding health care are reluctant to fund molecular genetic testing, unless there is clear evidence that the results of the testing would accurately predict the clinical status of the patient and affect their clinical management. Patients whose clinical situation does not fulfil their criteria will often be able to obtain testing as part of a research study or need to self-pay.
The current costs of molecular investigations are still a significant barrier to testing, but as the costs decrease, it is likely that molecular diagnosis will become more widely available. Professor Michaelides of Clinica London is excited that inherited retinal disease is entering a new era. He is a leading expert in the field of IRD and can advise you on your diagnosis and risk of passing the IRD on as well as your visual prognosis.