TPI1 and triosephosphate isomerase deficiency: Abnormal dimerization behavior of the pathogenic TPI variants has often been discussed as a feature in the pathogenesis of TPI deficiency due to the fact that several mutations within the TPI gene could influence the dimerization properties of the enzyme [2], e.g., bioinformatic predictions based on domain assignments suggested that the most common mutation at position 104 in the TPI gene, which is located in close proximity to the TPI dimerization interface, might affect the dimerization property of TPI ([2], [14] and Fig. 1).