sentences:  The disease is exceptionally rare with fewer than 100 patients diagnosed worldwide.Thirteen different mutations in the respective gene, which is located at chromosome 12p13 and encodes the ubiquitous housekeeping enzyme triosephosphate isomerase (TPI), have been discovered so far.TPI is a crucial enzyme of glycolysis and catalyzes the interconversion of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.