Molecular characterization of six new cases of red blood cell hexokinase deficiency yields four novel mutations in HK1

Hexokinase (HK) is a key enzyme of glycolysis, the only metabolic pathway able to provide the red blood cell with ATP. HK deficiency is a very rare hereditary disorder with severe chronic nonspherocytic hemolytic anemia (HNSHA) as a major clinical feature. To date, only 24 patients with HK deficiency have been identified. Here, we report the molecular analysis of six new cases of HK deficiency. A total of six different mutations were detected in HK1, four of them described here for the first time: c.2599C > T p.(His867Tyr), c.1799C > T p.(Thr600Met), c.873-2A > G and c.493-1G > A. The pathogenic nature of the identified missense mutations was confirmed by biochemical and 3-dimensional structural analysis. The effects of the novel splice site mutation c.873-2A > G were studied at the level of pre-mRNA processing, and confirmed at the protein level. All together, these results provide a better insight into the pathogenesis of this rare red cell disorder, and contribute to a better understanding of the genotype-phenotype correlation in HK deficiency.