Zhu et al (2013) examined evidence to uncover an association between MTHFR C677T  and the risk of PD, with overall risk found to be increased in European populations compared with Asian populations. Article Here  

Research conducted by Davis et al (2014) found patients prescribed Methotrexate (MTX) for diagnosed rheumatoid arthritis had a 3.05 increased risk of adverse events in the presence of the A1298C mutation. Article Here