Pyruvate kinase (PK) deficiency is a rare autosomal recessive disorder characterized by chronic hemolytic anemia of variable severity. Nine Polish patients with severe hemolytic anemia but normal PK activity were found to carry mutations in the PKLR gene encoding PK, five already known ones and one novel (c.178C > T). We characterized two of the known variants by molecular modeling (c.1058delAAG) and minigene splicing analysis (c.101-1G > A). The former gives a partially destabilized PK tetramer, likely of suboptimal activity, and the c.101-1G > A variant gives alternatively spliced mRNA carrying a premature stop codon, encoding a severely truncated PK and likely undergoing nonsense-mediated decay.

UNASSIGNED: Red cell pyruvate kinase deficiency (PKD) is a defect of glycolysis causing congenital non-spherocytic hemolytic anemia. PKD is transmitted as an autosomal recessive trait. The clinical features of PKD are highly variable, from mild to life-threatening anemia which can lead to death in the neonatal period. Most patients with PKD must receive regular transfusions in early childhood and as a consequence suffer from iron overloading.
UNASSIGNED: Here, we report a Polish family with life-threatening hemolytic anemia of unknown etiology. Whole exome sequencing identified two heterozygous mutations, c.1529 G > A (p.R510Q) and c.1495 T > C (p.S499P) in the PKLR gene. Molecular modeling showed that the both PKLR mutations are responsible for major disturbance of the protein structure and functioning. Despite frequent transfusions the patients do not show any signs of iron overload and hepcidin, a major regulator of iron uptake, is undetectable in their serum. The patients were homozygous for the rs855791 variant of the TMPRSS6 gene which has earlier been shown to down-regulate iron absorption and accumulation.
UNASSIGNED: The lack of iron overload despite a reduced level of hepcidin in two transfusion-dependent PKD patients suggests the existence of a hepcidin-independent mechanism of iron regulation preventing iron overloading.

Congenital non-spherocytic hemolytic anemia (CNSHA) is a rare autosomal recessive condition that presents as a congenital hemolytic anemia. The absence of vital enzymes required for glycolysis such as homozygous glucose phosphate isomerase (GPI) and red blood cell (RBC) nucleotide metabolism predisposes the RBCs to hemolysis. No spherocytosis is seen on peripheral smear as well as no signs of immune-mediated destruction of RBCs. We present a rare case of a previously healthy 21-year-old female patient with CNSHA from India.