ProQR Therapeutics N.V. announced that it received Fast Track designation from the Food and Drug Administration (FDA) for QR-421a. QR-421a is a first-in-class investigational RNA-based oligonucleotide designed to address the underlying cause of the vision loss associated with Usher syndrome type 2 and non-syndromic retinitis pigmentosa (RP) due to mutations in exon 13 of the USH2A gene. Fast Track designation is granted by FDA to drugs that are under development for serious conditions and have the potential to fulfill an unmet medical need. It was established with the intention to bring promising drugs to patients sooner by facilitating the development with more frequent FDA interactions and expediting the review process. About QR-421a: QR-421a is a first-in-class investigational RNA-based oligonucleotide designed to address the underlying cause of vision loss in Usher syndrome type 2 and non-syndromic retinitis pigmentosa (RP) due to mutations in exon 13 of the USH2A gene. Mutations in this exon can cause loss of functional usherin protein that causes the disease. QR-421a is designed to exclude the genetic defect from the RNA in the eye, such that it leads to the expression of a shortened but functional usherin protein, thereby modifying the underlying disease. QR-421a has received orphan drug designation in the United States and the European Union. About Usher Syndrome: Usher syndrome is the leading cause of combined deafness and blindness. Patients with this syndrome generally progress to a stage in which they have very limited central vision and moderate to severe deafness. Usher syndrome type 2 is one of the most common forms of Usher syndrome and is caused by mutations in the USH2A gene. To date, there are no approved treatments or products in clinical development that treat the vision loss associated with Usher syndrome type 2.