COMT and Parkinson disease: Recently the groundwork has been laid for evaluating PD gene loci in non-Europeans through a very large genetics study of PD, validating the value of genetic testing for diagnostic and therapeutic purposes in PD [18], and studies specific to South Asians are more easily accomplished with appreciable results in countries that have large genome databases, such as was recently performed in Great Britain where polymorphisms of COMT and other critical pharmacogenes were discovered in two South Asian groups [19].