The National Eye Institute has announced the discovery of a new type of macular
dystrophy. Researchers, who have not yet named the new macular dystrophy, detailed their findings in JAMA Ophthalmology.
Mutations in several genes are behind the central vision loss that macular dystrophies cause. Mutations can occur in several genes including ABCA4, BEST1, PRPH2, and TIMP3.
Patients with TIMP3 mutations typically develop symptoms in adulthood. The retinal epithelium (RPE) layer secrets the TIMP3 protein, which regulates retinal blood flow. The genetic mutations have been discovered in the mature protein after it has been removed from the RPE cells during the cleavage process.
Researchers discovered that two patients with the TIMP3 variation did not have the mature protein but instead, had the variant in the short signal sequence used by the gene to remove the protein from the cells. Clinical evaluations and genetic testing of the patients' family members was conducted to confirm the two new TIMP3 variants.