Pyruvate kinase (PKLR) is a critical erythrocyte enzyme that is required for glycolysis and production of ATP. Pyruvate kinase deficiency (PKD) is the most frequent red blood cell enzyme abnormality of the glycolytic pathway and the most common cause of hereditary nonspherocytic hemolytic anemia. Over 250 PKLR-gene mutations have been described, including missense/nonsense, splicing and regulatory mutations, small insertions, small and gross deletions, causing PKD and hemolytic anemia of variable severity. PKLR expression was increased in liver metastases as well as in primary colorectal tumors of patients with metastatic disease. PKLR protein variants may affect the frequency, and the intensity of malaria episodes induced by different Plasmodium parasites in humans living in areas of endemic malaria.