title: Life-threatening nonspherocytic hemolytic anemia in a patient with a null mutation in the PKLR gene and no compensatory PKM gene expression.
abstract: Human erythrocyte R-type pyruvate kinase (RPK) deficiency is an autosomal recessive disorder produced by mutations in the PKLR gene, causing chronic nonspherocytic hemolytic anemia. Survival of patients with severe RPK deficiency has been associated with compensatory expression in red blood cells (RBCs) of M2PK, an isoenzyme showing wide tissue distribution. We describe a novel homozygous null mutation of the PKLR gene found in a girl with a prenatal diagnosis of PK deficiency. The mutant PK gene revealed an 11-nucleotide (nt) duplication at exon 8, causing frameshift of the PKLR transcript, predicting a truncated protein inferred to have no catalytic activity. Western blot analysis and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) detected no M2PK expression in the peripheral blood red cell fraction. The expression of mutant RPK mRNA in the RBCs was almost 6 times higher than that detected in a control patient with hereditary spherocytosis. This molecular phenotypic analysis of the null mutation in the PKLR gene provides evidence for a lack of M2PK in the mature RBCs of this patient and suggests that normal red cell functions and survival are achieved through a population of young erythroid cells released into the circulation in response to anemia.
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Universidad Complutense de Madrid, Spain.
authors.forename: Amalia
authors.initials: A
authors.lastname: Diez
authors.forename: Florinda
authors.initials: F
authors.lastname: Gilsanz
authors.forename: Joaquin
authors.initials: J
authors.lastname: Martinez
authors.forename: Susana
authors.initials: S
authors.lastname: Pérez-Benavente
authors.forename: Néstor W
authors.initials: NW
authors.lastname: Meza
authors.forename: José M
authors.initials: JM
authors.lastname: Bautista
mesh_terms: D000746:Anemia, Hemolytic, Congenital Nonspherocytic / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D002648:Child; D004252:DNA Mutational Analysis; D005091:Exons; D005192:Family Health; D005260:Female; D006801:Humans; D008297:Male; D020125:Mutation, Missense; D011770:Pyruvate Kinase / Q000172:deficiency* / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013030:Spain / Q000453:epidemiology
chemical_list: D012333:RNA, Messenger; D011770:Pyruvate Kinase