The presence of IDHmut in glioma leads to a significant reduction in Gln and Glu levels, whereas IDHwt gliomas contain high levels of intracellular Glu [87,88], providing Pro for collagen biosynthesis through the activity of two enzymes: aldehyde dehydrogenase 18 family member A1, coded by ALDH18A1, and pyrroline-5-carbohydrate reductase 1, coded by PYCR1. Here, PYCR1 is linked to central nervous system cancer.