HTRA2 and Parkinson disease: This gene belongs to the HTRA serine protease family, including HTRA1, which is one of the first loci to be associated with AMD because of the strong linkage disequilibrium (LD) with AMRS2. In addition, HTRA2 has been linked to Parkinson’s Disease (PD), suggesting that it may represent a common triggering factor of both disorders [21].