Red cell pyruvate kinase deficiency: 17 new mutations of the PK‐LR gene

Abstract

Summary The PK‐LR gene was studied in 23 patients with congenital haemolytic anaemia associated with erythrocyte pyruvate kinase (PK) deficiency. Twenty‐seven different mutations were detected among the 42 mutated alleles identified: 19 missense mutations, four splice site mutations and one nonsense, one single base deletion and two large deletions. Seventeen of them (107G, 278T, 403T, 409A, 661A, 859C, 958A, 1094T, 1190T, 1209A, 1232C, 1369G, 507A, IVS9 −1c, IVS9 +43t, del C224, del 5006bp IVS3→ nt 1431) were new. Although all the exons, the flanking regions and the promoter were sequenced in all cases, we failed to detect the second expected mutation in four subjects. To correlate genotype to phenotype, the molecular results were related to the biochemical properties of the mutant enzymes by an analysis of the three‐dimensional structure of erythrocyte PK. The new mutant 409A, found in association with the large deletion of 5006 bp in a newborn baby who died soon after birth, was functionally characterized by mutagenesis and in vitro expression of the protein to investigate its contribution in the severity of the clinical pattern. However, the biochemical data obtained for the mutant enzyme cannot explain the severe anaemia found in the PK‐deficient patient hemizygous for this mutation.

Cholestasis and Hepatic Failure in a Neonate: A Case Report of Severe Pyruvate Kinase Deficiency

“…5 PK is an essential enzyme for the erythrocyte energetic metabolism, because maturation of the RBC is totally dependent on the adenosine triphosphate (ATP) generated by glycolysis, which maintains its integrity and function. [3][4][5][6] ATP deficiency induces irreversible membrane injury, leading to premature erythrocyte destruction in the spleen and liver. 7 It also reduces the erythrocyte capacity to protect itself against destruction from free radicals and oxidative stress.…”

Regulation of pyruvate metabolism and human disease

“…Numerous etiologies for PKR deficiency have been characterized, including point mutations, frameshift mutations, and large deletions within the PKR gene [15–17, 20–22]. Although some mutations affecting PKR will also affect PKL, liver dysfunction is very rarely observed [23].…”

Fifteen novel mutations inPKLRassociated with pyruvate kinase (PK) deficiency: Structural implications of amino acid substitutions in PK

“…Hence, future studies may be aimed at investigating the effect of the naturally occurring p.Thr48_Thr53 mutant on proteolytic processing to gain more insight into the role of (removal of) the N-terminal part of PK-R in erythroid-specific regulation of PK. The c.1618137_2064del1477 mutation is one of the few large deletional mutants detected in PKLR [Baronciani and Beutler, 1995;Costa et al, 2005;Fermo et al, 2005Fermo et al, , 2007. The deletion spans 1,477 bp.…”