In Parkinson’s disease (PD) and Huntington’s disease (HD) significantly higher MPO protein levels have been revealed in the midbrain and in caudate nucleus samples, respectively, whereas in amyotrophic lateral sclerosis (ALS), no differences have been detected in motor cortex samples compared with control cases (Choi et al. 2005). This evidence concerns the gene MPO and amyotrophic lateral sclerosis.