A team of researchers has discovered a new genetic eye disease that affects the macula, which is a small part of the light sensing retina we need for sharp, central vision.
The scientists are from the National Eye Institute (NEI) and shared their findings in JAMA Ophthalmology.
This new macular dystrophy is so novel that it is yet to be named, however.
Usually, macular dystrophies cause central visual loss due to mutations in a number of different genes, including PRPH2, ABCA4, BEST1, and TIMP3.
The lead author of the study, Bin Guan, shared that “We found it surprising that two patients had TIMP3 variants not in the mature protein, but in the short signal sequence the gene uses to ‘cut’ the protein from the cells. We showed these variants prevent cleavage, causing the protein to be stuck in the cell, likely leading to retinal pigment epithelium toxicity.”
This is because, for instance, those who suffer with Sorsby Fundus Dystrophy, which is linked to TIMP3, tend to develop symptoms as adults.
Often, they experience sudden changes in visual acuity because of new and abnormal blood vessels that grow under the retina and leak fluid that affects sight.
These findings were followed by clinical evaluations and genetic testing of the patients’ family members in order to confirm that the two new TIMP3 variants are really linked to this atypical maculopathy.
Medical retina specialist, Cathy Cukras, who evaluated the patients, stated that “Affected individuals had scotomas, or blind spots, and changes in their maculas indicative of disease, but, for now, they have preserved central vision and no choroidal neovascularization, unlike typical Sorsby Fundus Dystrophy.”
Senior author of this study and director of the Ophthalmic Genomics Laboratory at NEI, Rob Hufnagel, also mentioned that “Discovering novel disease mechanisms, even in known genes like TIMP3, may help patients that have been looking for the correct diagnosis, and will hopefully lead to new therapies for them.”