Glucose metabolism in fibroblasts from patients with erythrocyte hexokinase deficiency

Four different hexokinase (HK) isoenzymes are distributed in different proportions in human tissues. Fibroblasts contain HK type I as the predominant glucose phosphorylating activity, the same isoenzyme that predominates in red blood cells (RBC). We have established cell lines from two patients homozygous for RBC HK deficiency but carrying different mutations. In one case (HK-Melzo) the residual RBC enzyme shows a marked heat instability but possesses normal kinetic and regulatory properties; in the other (HK-Napoli), the enzyme is characterized by an increased Ki for glucose-1,6-diphosphate. These properties are also retained by the fibroblasts' hexokinase. Glucose utilization by cultured fibroblasts from these patients was markedly reduced in the cell lines where HK deficiency was more pronounced. However, cells with only 30% HK activity retained their full ability to utilize glucose in the hexose monophosphate pathway. This was shown to be true not only under basal conditions but also in the presence of oxidative agents such as methylene blue. Significant reduction of the ATP level was also found in HK-Melzo fibroblasts. Thus, HK deficiency is associated with reduced glucose utilization and normal hexose monophosphate shunt rates. Results previously obtained on RBC support similar conclusions.     

Hereditary nonspherocytic hemolytic anemia due to a new hexokinase variant with reduced stability

A 27-year-old woman with severe chronic hemolytic anemia was found to have reduced red cell hexokinase activity when the degree of reticulocytosis was considered. This enzyme had normal pH-dependent activity, normal Km for glucose, fructose, and mannose, normal Km for Mg adenosine triphosphate (ATP)2- and Ki for glucose-1,6-diphosphate. Furthermore, the pH-dependence and orthophosphate dependence of Ki for glucose-1,6-diphosphate were normal. However, this hexokinase was inactivated rapidly at 44 degrees C. No abnormalities were found in the red cell hexokinase isozymic pattern when it was compared with the profile obtained from cells of similar age. The hexokinase specific activity was reduced in all the red blood cell fractions obtained by density gradient ultracentrifugation; a marked difference in the distribution of cells through the gradient was evident. Among the glycolytic intermediates, a significant decrease of 2,3- diphosphoglycerate was evident. ATP and glucose 6-phosphate were also reduced when compared with cells of similar. Glucose consumption of the hexokinase-deficient cells decreased, but the rate of glucose metabolized through the hexose monophosphate shunt was unchanged. Although the total hexokinase activity in lymphocytes was only reduced by 37%, a marked hexokinase deficiency was detected in blood platelets (20% to 25% of normal activity). The parents and one of two siblings of the patient were heterozygous for the defect, with 66% to 74% of normal erythrocyte hexokinase activity and reduced heat stability of the enzyme. These results, when compared with those obtained in previously reported cases of hexokinase deficiency, provide further evidence of the broad phenotypic variability that characterizes this disorder. Furthermore, it is suggested that failure of energy generation is probably the primary cause of hemolytic anemia in hexokinase deficiency.     

The polyglandular deficiency syndrome: a new variant in Persian Jews

Five Persian Jews were detected with the polyglandular deficiency syndrome (PDS). Primary hypoparathyroidism and hypogonadism were present in each, adrenal insufficiency in two, and insulin-dependent diabetes mellitus and latent hypothyroidism in single subjects. The percentage of T and B cells, and the mononuclear cell response to phytohemagglutinin and Concanavalin A were normal in all five. IgG and IgA levels and the OKT4+/OKT8+ cell ratio were low in one subject. Antinuclear and antithyroid antibodies were present in one subject. HLA-DR5 was present in 4/4, HLA-24 and B5 (B51) in 3/4 subjects. A single case of isolated hypoparathyroidism (IHP) was detected among 12 first degree relatives. HLA antigens B8, DR3, were absent in all of these subjects. Seven non-Iranian Jews with IHP were also examined. HLA A26 or A25 were present in all seven. Persian Jews appear to have a unique variant of PDS.     

DNACJ12 deficiency in patients with unexplained hyperphenylalaninemia: two new patients and a novel variant

Metabolic Brain Disease - In addition to tetrahydrobiopterin deficiencies and phenylalanine hydroxylase deficiency (phenylketonuria) due to PAH variants, the deficiency of the co-chaperone protein...     

Platelet functions and energy metabolism in a patient with hexokinase deficiency

We have studied the regeneration of adenosine triphosphate (ATP) in the glycolytic pathway in platelets with a 75% reduction in hexokinase (HK) activity and have investigated aggregation and Ca2+ secretion. HK- deficient platelets had a normal glycolytic flux in the resting state, but responded insufficiently to stimulation with thrombin (5 U/ml). In contrast, glycogen contents and glycogenolysis were normal. When the metabolic adenine nucleotides were labeled with 14C-adenine, the patient's platelets showed a normal adenylate energy charge and a normal level of 14C-ATP. However, the inhibitor of mitochondrial energy generation, CN-, induced a weaker fall in 14C-ATP in the patient's platelets than in the controls. Analysis of secretion markers revealed decreased amounts of granule-bound ATP and secretable Ca2+, whereas granule-bound adenosine diphosphate (ADP), beta-thromboglobulin, N- acetyl-beta-D-glucosaminidase, and beta-glucuronidase were within the normal range. Aggregation and Ca2+ secretion induced by 5 U/ml thrombin were normal and were not changed in the presence of inhibitors of mitochondrial and glycogenolytic energy generation. Aggregation was also normal at 0.1 U/ml thrombin and was independent of these inhibitors, but Ca2+ secretion was greatly impaired when mitochondrial and glycogenolytic ATP resynthesis was abolished. These findings indicate that a severe reduction in HK activity causes insufficient acceleration of the glycolytic flux during stimulation with thrombin. This leads to impaired dense granule secretion in conditions where secretion depends on concurrent ATP resynthesis and glycolysis is rate limiting.     

Congenital nonspherocytic hemolytic anemia with an unstable hexokinase variant

We report a family with a new hexokinase variant that gives rise to nonspherocytic hemolytic anemia in one apparently homozygous family member. The variant enzyme has a normal pH optimum, normal reaction kinetics, and normal electrophoretic properties, but has reduced activity and is apparently inactivated rapidly as the affected erythrocytes age.     

Hemoglobin Saverne: a new variant with elongated beta chains: structural and functional properties

A 26-year-old French woman born in Saverne (France) was found to have Heinz body hemolytic anemia. Isoelectrofocusing showed the presence of an abnormal band amounting to 35% of the total hemoglobin concentration, suggesting a beta variant. Structural analysis of the abnormal beta chain showed an elongated C-terminal segment. Histidine 143 is replaced by a proline and the C-terminal sequence is identical to the corresponding segment of Hb Cranston. This new variant, named Hb Saverne, has beta chains composed of 156 amino acid residues. Studies of its functional properties showed that Hb Saverne is an unstable, high affinity variant with low cooperativity.     

A new abnormal variant of spectrin in black patients with hereditary elliptocytosis

Seven black patients with mild hereditary elliptocytosis (HE) from five unrelated families were studied. The erythrocytes of these patients exhibited an abnormal thermal sensitivity (between 45 degrees C and 47 degrees C instead of 49 degrees C). An important defect of spectrin dimer self-association was detected in two ways: (1) the proportions of spectrin dimer (SpD) extracted from membranes at 4 degrees C under low ionic strength conditions were increased between 25% and 56% (normal value 15% +/- 2%); (2) the spectrin dimer----tetramer conversion in solution were defective with an association constant value between 0.4 and 2.4 X 10(5) M-1 for a normal value of 6 +/- 0.4 X 10(5) M-1. Spectrin (Sp) from HE patients and normal volunteers (32 black and 22 white subjects) was submitted to limited tryptic digestion, followed by one- or two-dimensional separation of the peptides. Peptide patterns of crude Sp from all seven HE patients exhibited a marked and reproducible decrease in 80,000-dalton peptide (previously identified as the dimer- dimer interaction domain of the alpha-chain) and a concomitant appearance of a novel 65,000-dalton peptide. A minor fragment at 28,000 daltons was also decreased. Tryptic digestion of HE spectrin dimer and tetramer (SpT), isolated after the SpD self-association procedure in solution, revealed modifications (decrease in the 80,000-dalton peptide and presence of a 65,000-dalton peptide) predominantly in HE SpD when peptide patterns of HE SpT were quite similar to control SpT patterns. Immunoblots with anti-alpha-chain antibodies revealed that the 65,000- dalton peptide derived from the alpha-chain. Kinetic studies of Sp digestion showed that the 65,000-dalton peptide did not result from further digestion of a 74,000 intermediate and was not a precursor of 46,000- to 50,000-dalton peptides. These results show a new structural defect of Sp-alpha-chain, associated with a defective Sp dimer self- association in HE.     

Correction to: DNAJC12 deficiency in patients with unexplained hyperphenylalaninemia: two new patients and a novel variant

Metabolic Brain Disease - A Correction to this paper has been published: https://doi.org/10.1007/s11011-021-00759-8     

Hexokinase deficiency in erythrocytes: a new variant in 5 members of a Finnish family.

15 cases of congenital haemolytic anaemia have thus far been attributed to hexokinase (HK) deficiency in erythrocytes. We report some clinical, biochemical and genetic findings from 5 members of a Finnish family with this deficiency. The proband, a 1-year-old girl, was the only patient with anaemia. All subjects had either mild or marked reticulocytosis. Red cell ATP levels were at the lower range of normal in all subjects and 2,3-DPG was abnormally low in one. The activities of red cell enzymes, other than HK, were within or above the normal range, respectively. The Km-values for glucose and fructose were elevated (ATP normal) in the subjects with HK deficiency. We speculate that the family represents heterozygosity of a mutant allele and that there is phenotypic variation associated with the HK mutant. The locus might be subject to mutations which lead to a variety of HK variants and to a spectrum of diseases. This point of view is in accordance with the overwhelming variation of reaction kinetics and metabolic effects of this and other reported cases.     

Heterogeneity of hereditary methaemoglobinaemia: a study of 4 Cuban families with NADH-Methaemoglobin reductase deficiency including a new variant (Santiago de Cuba variant)

NADH-methaemoglobin reductase deficiency has been found in 4 Cuban families; 3 subjects carried the mild form of the deficiency while in 2 sibs of the fourth family the deficiency was associated with neurological involvement. The parents in this family were consanguinous and the sibs were shown to be homozygous for a new fast electrophoretic variant. It was named Diaphorase Santiago de Cuba.     

Complementation studies with clinical and biochemical characterizations of a new variant of multiple sulphatase deficiency

A patient with a new variant of multiple sulphatase deficiency (MSDv) is reported. Unlike the usual type, onset was late and progress was slow. The phenotypic changes were those usually seen in multiple sulphatase deficiency but much milder. Cytoplasmic accumulations were found in skin fibroblasts, and urinary mucopolysaccharides and sulphatides were high. Arylsulphatases A, B and C (ASA, B and C), heparan N-sulphatase sulphoiduronate sulphatase, andN-acetylgalactosamine 6-sulphatase all had low activity in lymphocytes and cultured skin fibroblasts. Complementation for ASA activity was found in hybrids between MSDv and metachromatic leukodystrophy (MLD) as well as between multiple sulphatase deficiency (MSD) and MLD. Complementation for ASC activity was also seen in hybrids between MSDv and X-linked ichthyosis (XLI), and between MSD and XLI. However, neither ASA nor ASC activity increased in hybrid cells of MSDv and MSD. These results suggested that the mutations of MSDv and of MSD were allelic, although of different phenotypes.     

6-Phosphogluconolactonase deficiency, a hereditary erythrocyte enzyme deficiency: possible interaction with glucose-6-phosphate dehydrogenase deficiency.

Partial deficiency of 6-phosphogluconolactonase (EC 3.1.1.31) of the erythrocytes was discovered as an autosomal dominant disorder. Hemolytic anemia occurred in an individual who had inherited both the gene for 6-phosphogluconolactonase deficiency and that for deficiency of a nonhemolytic variant of glucose-6-phosphate dehydrogenase (EC 1.1.1.49). It is proposed that the interaction of this hereditary erythrocyte abnormality with glucose-6-phosphate dehydrogenase deficiency may explain hemolysis in some other patients who have inherited polymorphic variants of glucose-6-phosphate dehydrogenase.     

Red cell glucose-6-phosphate dehydrogenase deficiency in Finland. Characterization of a new variant with severe enzyme deficiency.

Severe red cell glucose-6-phosphate dehydrogenase (G-6-PD) deficiency has been found in an 'aboriginal' Finnish family. 2 male and 9 female carriers of the variant G-6-PD were studied. The genetic pattern is consistent with x-linked recessive inheritance and the defect is associated with drug (primaquine) induced haemolysis. This was demonstrated by enzyme deficient red cell (51Cr-labelled) survival studies on a normal volunteer recipient. In addition, one of the hemizygotes studied had a slight chronic nonspherocytic haemolytic disorder. The partially purified enzyme had many of the characteristics of G-6-PD Mediterranean. The occurrence of this G-6-PD Mediterranean type variant in the Finnish population, which differs greatly from Mediterranean ethnic groups, as well as the association of slight chronic haemolysis with severe G-6-PD deficiency is discussed.     

Erythrocyte pyruvate kinase deficiency: Characterization of a new variant (PK “Aarau”)

Summary A new PK variant with moderate hemolytic anemia is described. The enzymes of the nonanemic parents show sigmoidal reaction kinetics, with normal kinetic parameters, but differ with respect to nucleotide specificity, thermostability, and the concentrations of the glycolytic intermediates in the erythrocytes.The most characteristic features of the patient's (daughter) enzyme are a 30% activity, hyperbolic reaction kinetics and only two bands in the SDS-gel electrophoresis instead of three bands observed with the parental enzymes. Moreover, the pH-optimum is shifted to the acidic range, the affinity for PEP and ADP is decreased, ATP inhibition is negligible and FDP-activation is roughly ten times smaller than with controls. The concentrations of 2.3-DPG, 2-PG and PEP in the erythrocyte are increased, but ATP decreased.As there is no consanguinity in the parents and their enzymes are different this PK mutant can be considered to be compound-heterozygous for two different mutant PK alleles.     

Glucosephosphate isomerase deficiency type Liège: A new variant with congenital nonspherocytic hemolytic anemia

Summary GPI deficiency was detected in a three year old girl of Morrocan origin suffering, since birth, from hemolytic anemia. The defective GPI is very thermolabile and migrates on starch gel electrophoresis as a single band with a mobility of 96 % of the normal main band.The purification of the patient's GPI resulted in a 16000-fold enriched preparation, free of any other enzyme activity. The yield was 35 %. The purified enzyme was very unstable even at low temperature. The kinetic constants of the forward and backward reaction as well as the inhibitory constants of 2,3-DPG and 6-PG do not significantly differ from normal values. The bio-chemical properties of the patient's GPI indicate a new variant designated type Liège.     

Juvenile dermatomyositis presenting with anasarca: a possible new variant

Juvenile dermatomyositis is a rare autoimmune disease characterized by inflammation of the muscle skin and other organs. Although localized edema is a common feature of juvenile dermatomyositis generalized edema has been reported infrequently. We describe a patient with dermatomyositis and anasarca and present a brief review of the literature.