Eight cases from six families had a biochemical diagnosis of enzyme defect; two were confirmed to have pyruvate kinase (PK) deficiency, three from two families glucose-6-phosphate dehydrogenase (G6PD) deficiency and one was found to have one mutation in GPI gene, in compound heterozygosity with the polymorphism c.489A > G (p.Gly163 = rs1801015), possibly associated to splicing alterations (Fermo et al., 2019); in two related cases no mutations in PKLR gene were found in spite of a slightly decreased PK activity detected by enzymatic assay. The gene discussed is GPI; the disease is pyruvate kinase deficiency of red cells.