Five to seven pQTL were observed for phosphoglycerate mutase 1 (PGAM1), the putative Parkinson disease autosomal recessive early onset 7 variant 1 (PARK7), triose phosphate isomerase (TPI1), peroxiredoxin 4 (PRDX4), malate dehydrogenase 1 (MDH1) and 3-hydroxyanthranilate 3,4-dioxygenase (HAAO). This evidence concerns the gene MDH1 and Parkinson disease.