Six novel variants in the PKLR gene associated with pyruvate kinase deficiency in Argentinian patients.

BACKGROUND: Pyruvate kinase deficiency (PKD) is a rare recessive congenital hemolytic anemia caused by mutations in the PKLR gene. The disease shows a marked variability in clinical expression. We studied the molecular features of nine unrelated Argentinian patients with congenital hemolytic anemia associated with erythrocyte pyruvate kinase deficiency. DESIGN AND METHODS: Routine hematologic investigations were performed to rule out other causes of chronic hemolytic anemia. Sanger sequencing and in-sílico analysis were carried out to identify and characterize the genetics variants. RESULTS: Six different novel missense variants were detected among the 18 studied alleles: c.661 G > C (Asp221His), c.956 G > T (Gly319Val), c.1595 G > C (Arg532Pro), c.347 G > A (Arg116Gln), c.1232 G > T (Gly411Val), c.1021G > A (Gly341Ser). Structural implications of amino-acid substitutions were correlated with the clinical phenotypes seen in the probands. CONCLUSIONS: This is the first comprehensive report on molecular characterization of pyruvate kinase deficiency in Argentina and the second from South America that would contribute to our knowledge on the distribution and frequency of PKLR variants in our population but also offer new insights into the interpretation of the effect of PKLR variants and phenotype.

Differential effects on enzyme stability and kinetic parameters of mutants related to human triosephosphate isomerase deficiency.

Human triosephosphate isomerase (TIM) deficiency is a very rare disease, but there are several mutations reported to be causing the illness. In this work, we produced nine recombinant human triosephosphate isomerases which have the mutations reported to produce TIM deficiency. These enzymes were characterized biophysically and biochemically to determine their kinetic and stability parameters, and also to substitute TIM activity in supporting the growth of an Escherichia coli strain lacking the tim gene. Our results allowed us to rate the deleteriousness of the human TIM mutants based on the type and severity of the alterations observed, to classify four "unknown severity mutants" with altered residues in positions 62, 72, 122 and 154 and to explain in structural terms the mutation V231M, the most affected mutant from the kinetic point of view and the only homozygous mutation reported besides E104D.

First-trimester prenatal diagnosis of pyruvate kinase deficiency in an Indian family with the pyruvate kinase-Amish mutation.

Pyruvate kinase (PK) deficiency is a rare red cell glycolytic enzymopathy. The purpose of the present investigation was to offer prenatal diagnosis for PK deficiency to a couple who had a previous child with severe enzyme deficiency and congenital non-spherocytic hemolytic anemia. PK deficiency was identified in the family by assaying the enzyme activity in red cells. Chorionic villus sampling was performed in an 11-week gestation and the mutation was located in exon 10 of the PKLR gene characterized by polymerase chain reaction and using restriction endonuclease digestion with the MspI enzyme, which was confirmed by DNA sequencing on the ABI 310 DNA sequencer. Both the parents were heterozygous for the 1436G-->A [479 Arg-->His] mutation in exon 10 and the proband was homozygous for this mutation. The fetus was also heterozygous for this mutation and the pregnancy was continued. Prenatal diagnosis allowed the parents with a severely affected child with PK deficiency to have the reproductive choice of having the fetus tested in a subsequent pregnancy.

First-trimester prenatal diagnosis of pyruvate kinase deficiency in an Indian family with the pyruvate kinase-Amish mutation

Pyruvate kinase (PK) deficiency is a rare red cell glycolytic enzymopathy. The purpose of the present investigation was to offer prenatal diagnosis for PK deficiency to a couple who had a previous child with severe enzyme deficiency and congenital non-spherocytic hemolytic anemia. PK deficiency was identified in the family by assaying the enzyme activity in red cells. Chorionic villus sampling was performed in an 11-week gestation and the mutation was located in exon 10 of the PKLR gene characterized by polymerase chain reaction and using restriction endonuclease digestion with the MspI enzyme, which was confirmed by DNA sequencing on the ABI 310 DNA sequencer. Both the parents were heterozygous for the 1436G-->A [479 Arg-->His] mutation in exon 10 and the proband was homozygous for this mutation. The fetus was also heterozygous for this mutation and the pregnancy was continued. Prenatal diagnosis allowed the parents with a severely affected child with PK deficiency to have the reproductive choice of having the fetus tested in a subsequent pregnancy.

Glucose-6-phosphate dehydrogenase Durham: a de novo mutation associated with chronic hemolytic anemia.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme defect. We report a new variant, G6PD Durham713G, that is associated with chronic nonspherocytic hemolytic anemia. The G6PD Durham713G variant has a unique biochemical and enzymatic profile and a novel A-->G substitution mutation at nucleotide 713, changing lysine to arginine at amino acid 238. This mutation was not found in the mother of our patient, indicating that G6PD Durham713G resulted from a de novo mutation.

[Chronic non-spherocytic hemolytic anemia caused by pyruvate kinase deficiency in a Costa Rican family carrying hemoglobin C disease]. / Anemia hemolítica crónica no esferocítica (AHCNE) por déficit de piruvato quinasa (PK) en una familia costarricense portadora de hemoglobinopatía C.

The two first homozygous (or double heterozygous) cases of pyruvate kinase (PK) deficiency found in a Costa Rica family with no signs of consanguinity are reported. The clinical manifestations of the deficiency were present in both cases, these being enhanced in one of them by pregnancy. The family study performed showed the heterozygous character of the PK deficiency in all cases, plus the demonstration in two instances (father and brother) of a heterozygous haemoglobin C disease. The importance of the PK/HK quotient in the identification of the PK deficiency heterozygous is stressed, especially when the enzyme activity registered from haemolysates falls within the normal range.

G-6-PD Guadalajara. A new mutant associated with chronic nonspherocytic hemolytic anemia.

This paper describes a new G-6-PD variant designated Guadalajara, which was found in a Mexican boy suffering from chronic hemolytic anemia. The red cell enzyme activity of the subject is about 14%. The mutant enzyme showed rapid electrophoretic mobility, slightly increased affinity for glucose-6-phosphate, slightly decreased affinity for NADP+, moderately elevated utilization of substrate analogues, and normal heat stability, pH curve, and inhibition by NADPH. G-6-PD Guadalajara differs from all previously reported variants and is the first variant associated with chronic hemolysis found in Mexico.

G6PD-Puerto Limón: a new deficient variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia.

A new glucose-6-phosphate dehydrogenase (G6PD) variant with total deficiency associated with congenital nonspherocytic hemolytic anemia was found in a Costa Rican family. The study of the partially purified enzyme revealed thermal instability, increased G6P affinity, abnormal pH optimum, increased utilization of analogues, and a chromatographic behavior that differs from all the variants previously described. Thus, this new variant was designated G6PD Puerto Limón.

G6PD Varadero. A new variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia.

A glucose-6-phosphate dehydrogenase (G6PD) variant was studied in a mulatto patient with chronic nonspherocytic hemolytic anemia. This variant has reduced activity, increased thermolability, a reduced Michaelis constant for glucose-6-phosphate, slightly increased electrophoretic mobility, a biphasic pH activity profile, high 2-deoxyglucose-6-phosphate utilization, normal diamino nicotinamide adenine dinucleotide phosphate utilization and a peak of elution profile after G6PD B. The electrophoretic, kinetic, and chromatographic properties of this erythrocyte G6PD variant allow the conclusion that G6PD Varadero is probably a new variant.

Glucose phosphate isomerase deficiency with hereditary nonspherocytic hemolytic anemia.

Eight children (5 living, 3 deceased) with severe hereditary nonspherocytic hemolytic anemia caused by glucose phosphate isomerase deficiency have been observed in two Kentucky and Indiana families. All affected children were severely anemic in early life. Three deaths occurred in young patients who did not receive adequate transfusions of blood or whose parents refused to permit splenectomy. Splenectomy generally abolishes the requirement for blood transfusion. No patient has required regular transfusion of blood after puberty. Growth and development have been surprisingly normal and no patient has died of infection. The anemia is expressed as an autosomal recessive trait, but the enzyme variant can be detected in hematologically normal heterozygotes. The abnormal isomerase molecule is heat labile and is contained in neutrophils and lymphocytes as well as in erythrocytes.