Retinitis pigmentosa is a low-prevalence, hereditary, degenerative disease of the retina which falls within the category of rare diseases. During adolescence the patients perceive a loss of night vision, and the loss of vision in the peripheral field of vision gradually increases until central vision also diminishes.  This disease is caused by mutations. “Today over 3,000 mutations in 107 genes associated with retinitis pigmentosa are known. Only 65% of the cases are known and 35% of the cases have yet to be discovered,” said the UPV/EHU’s ophthalmologist and lecturer Cristina Irigoyen.

The disease has been untreatable until now, but there are currently various treatments being developed for different stages of the disease. The last few years have seen great strides forward in gene therapy: pharmacological treatments are being sought for specific mutations. The advances achieved in gene therapy “have revolutionised the importance that the patients should have a genetic diagnosis so that as soon as a treatment is found for their specific mutation they are in pole position, or can participate in clinical trials,” explained Dr Irigoyen. Specifically, “over 30 clinical trials are up and running, and from the study carried out with patients in Gipuzkoa we have spotted 32 patients at Hospital Donostia who could benefit from the results of these clinical trials,” she pointed out.

Clinical and genetic diagnosis at the request of the patients

On the basis of the request made by Begisare, the association of patients with retinitis pigmentosa in Gipuzkoa, a full exploration has been made of the patients in Gipuzkoa and so a register has been produced for the purposes of correlating genetic and clinical aspects, in other words, “we have attempted to link certain mutations with the patients’ clinical aspects to be able to orientate the genetic studies:  it is easier to conduct the genetic study if you suspect a mutation in a specific gene,” explained Dr Irigoyen.

The UPV/EHU lecturer confirmed that the diagnosis is crucial in order to give the patient genetic advice and for dealing with the secondary complications that could be treated. Once the diagnosis has been made, it is possible to give the patient a prognosis for his/her disease: “Depending on the mutation in question, the prognosis could be better or worse,” she pointed out. What is more, as it is a hereditary disease, the patient can know whether he/she is going to pass the disease on to his/her offspring and “if he/she wishes to have children, he/she can be offered a pre-implantation genetic diagnosis at the fertility section at Hospital Donostia,” explained Irigoyen.

The study conducted by Cristina Irigoyen has established the bases with which numerous channels in advancing the research have been opened up: “This is a pioneering study, and we have managed to expand it to patients in Álava and Bizkaia”. What is more, at Biodonostia they have managed to set up a group to study retinitis pigmentosa from various points of view: expanding knowledge about the molecular mechanisms of the disease, testing new treatments in animal models, reviewing current clinical trials to see which could benefit the patients, participating in a multi-centre clinical trial of one therapy.

Additional information

Cristina Irigoyen-Laborra (1980, Iruñea-Pamplona) is an assistant lecturer in Ophthalmology at the UPV/EHU, and a clinician in Ophthalmology at Hospital Donostia and at Policínica Gipuzkoa. Irigoyen carried out this study within the framework of her PhD thesis entitled Estudio epidemiológico clínico y molecular de la Retinosis Pigmentaria en Gipuzkoa [Clinical and molecular epidemiological study of Retinitis Pigmentosa in Gipuzkoa]. Her supervisors were Javier Araiz-Iribarren (lecturer in Ophthalmology at the UPV/EHU and ophthalmologist at the Hospital San Eloy) and Javier Ruiz-Ederra (head of sensory neurodegeneration at the Biodonostia Institute). The clinical part of the study was conducted at University Hospital Donostia and the genetic study at the Biodonostia Institute for Research. The researchers worked in collaboration with Dr Cruchaga of the University of Washington, and Begisare, the association of patients in Gipuzkoa affected by retinitis pigmentosa.