TMEM175 and Parkinson disease: A haplotype block TMEM175/GAK/DGKQ (transmembrane protein 175/cyclin G associated kinase/theta diacylglicerol kinase) was first associated with sporadic PD in the GWAS performed by Hamza et al. after it was already confirmed to be associated with the familial form of the disease (Pankratz et al., 2009; Hamza et al., 2010).