IMPDH2 and Dystonia: Although it has not been directly shown that dystonia‐linked IMPDH2 mutations result in purine pool imbalance, findings from in vitro experiments demonstrating a gain of IMPDH2 function predict that the relative levels of adenine nucleotides would be disrupted by an increase in the ratio of GMP to AMP synthesis (see Figs 1 and 2).22