[Clinical significance and interpretation of red cell enzyme analyses]

Red cells have a life span of approximately 120 days and disturbances at biochemical pathways such as glycolysis, pentose phosphate shunt, nucleotide metabolism or glutathione synthesis/reduction systems lead to premature cell death, i.e. hemolysis. Red cell enzyme analysis is useful for screening for an enzyme defect which is responsible for hereditary nonspherocytic hemolytic anemia (HNSHA). Further clinical significance of red cell enzyme assay includes the diagnosis of paroxysmal nocturnal hemoglobinuria, methemoglobinemia, Diamond-Blackfan anemia, severe combined immune deficiency, glycogen storage disease, etc. Since several age-dependent enzymes are known, careful evaluation of enzyme activities is required if reticulocyte counts are elevated. It should be noted that deficiency of an isozyme may be masked by activity derived from another isozyme. Recent progress in the molecular genetics of red cell enzymopathies and protein structure-function mechanisms enable us to diagnose "enzyme deficiency" at DNA level.