One study found a mutation in the IFT122 gene in blind dogs. The genetic defect that has now been discovered leads to the progressive destruction of photoreceptor cells and retinal dystrophy. IFT122 is a new candidate for retinal dystrophy in humans as well. Based on the findings, a genetic test was developed to support breeding and diagnostics.
Inherited retinal dystrophy is a common cause of blindness. Up to two million people worldwide suffer from this disorder. No effective treatment is available for retinal dystrophies. Gene therapy is expected to provide a solution, but such therapies can only be developed if the genetic cause of the disease is known. Related mutations have been identified in more than 70 genes to date, but the genetic background of the disease is unknown in up to half of patients.
“Retinal dystrophy has been described in over 100 breeds of dogs. Related research will help identify new genes associated with racial blindness and pathogenic mechanisms. IFT122 is a good example and offers a possible explanation for unsolved cases in humans,” he said Professor Hannes Lohi says.
The study used data that included more than a thousand Lapponian Herders and Finnish Lapphunds from a canine DNA bank. Several retinal dystrophy genes have previously been described in both breeds.
“Among other things, two genes for eye diseases have already been identified at Lapponian Herders, but they are not responsible for all cases. In some dogs, the disease is caused by the IFT122 gene. The finding is significant because genetic tests can now differentiate between them.” Retinal dystrophies associated with different genes in races, making a difference in monitoring disease progression, making prognoses and developing novel treatments. The diagnostics are getting better and making the work of veterinarians easier, “explains Maria Kaukonen, doctor for veterinary medicine.
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The discovery of genes also makes it easier to understand retinal biology. IFT122 is part of a protein complex associated with ciliary function in the retina.
“The age of onset varies and the disease progresses slowly in some dogs. IFT122 is known to contribute to the transport of opsin in photoreceptor cells. The gene variant disrupts this transport and leads to progressive blinding. Since IFT122 is associated with the function of cilia, What is important to the body, we have examined some of the dogs more closely for other problems that may be related to cilia-related disorders, such as kidney abnormalities or serious developmental disorders of the internal organs. We have found that the damage appears to be this information help us understand how the gene works, “adds Kaukonen.
The results will also play a role in future plans to remove the disease from different races. In the Lapponian Herders and Finnish Lapphunds, the proportion of people who carried the gene variant was 28% and 12%, respectively.
“This is a recessive inherited disease, which means that a dog who becomes blind will inherit the variant from both parents who are both carriers of the variant. Genetic testing can help avoid carrier-carrier combinations, which makes it easy for sick dogs to be born Based on the study, a new concrete tool was developed for the benefit of the breeders, “says Lohi.
The new study is part of a larger research project by Professor Lohi’s research group on the genetic background of hereditary diseases. Kaukonen recently joined a research group at Oxford University that focused on developing gene therapies for retinal dystrophy. At the same time, Kaukonen and Lohi continue to work closely together to study a number of eye diseases together with Helsinki University Hospital and other operators.
“In canine research, there are many more genetic findings related to eye diseases. We are only at the beginning. Among other things, we are currently investigating the genetic background of glaucoma and corneal and retinal dystrophy in about 30 breeds. The preliminary results are promising,” says Lohi.