[Hexokinase deficiency in blood cells in a group of kin with familial panmyelopathy (Fanconi type)]

Fanconi anemia, dyskeratosis congenita, and WT syndrome

The association of congenital anomalies and pancytopenia is encountered in several clinical syndromes. Among these, Fanconi anemia is by far the most prevalent, and consequently best known. As a result, other similar conditions, such as dyskeratosis congenita and particularly WT syndrome, are often mistaken for Fanconi anemia. However, at a closer look, the type of congenital anomalies, the mode of inheritance, cytogenic and other laboratory findings allow clear differentiation between these 3 syndromes.

Human erythrocyte hexokinase deficiency: a new variant with abnormal kinetic properties

A 14-month-old child who had a haemolytic episode when he was 5 years old, and with psychomotor retardation, was found to have decreased red cell hexokinase activity. The mutant enzyme was characterized by an increased affinity for glucose associated with an increased inhibition constant for glucose-1,6-diphosphate. Affinity for Mg ATP2-, heat stability and pH-optimum were normal. The isozymic pattern of the red cell enzyme was normal but all the molecular forms were present in reduced amounts. The kinetics of decay of hexokinase during cell ageing was also normal. Glucose consumption of the hexokinase deficient cells was 60-65% of the controls while the amount metabolized through the hexose monophosphate shunt was unchanged. Red cell 2,3-diphosphoglycerate and glucose-6-phosphate levels were normal in the proband but reduced in the erythrocytes of his parents, who were heterozygous for the defect but had normal haematological data. Comparison with the 13 previously reported cases of hexokinase deficiency confirms the broad phenotypic variability that characterizes this disorder.

Proliferative kinetics and mitomycin C-induced chromosome damage in Fanconi's anemia lymphocytes

Lymphocytes from two sisters with Fanconi's anemia (FA) were studied for cell cycle kinetics, sister chromatid exchanges (SCEs), and chromosomal aberrations when they had undergone one, two, or three or more divisions in mitomycin C (MMC)-treated cultures. Lymphocytes from the parents, another sister of the probands, and a healthy unrelated adult were examined as controls. Analyses of cell cycle kinetics by the sister chromatid differential staining method revealed that the relative frequency of metaphase cells at their third or subsequent divisions was much smaller in untreated FA cultures than in normal cultures fixed at 96 h after phytohemagglutinin stimulation. These data indicate that FA cells proliferate much more slowly than normal cells. MMC treatments of FA and normal cells led to a clearly dose-related delay in cell turnover times, the duration of delay being much longer in FA than in normal cells. FA cells had about 1.4 times higher frequencies of SCEs than normal cells in both MMC-treated and untreated cultures. FA cells also showed several times higher frequencies of chromosomal aberrations than normal cells, and the frequency of chromosomal aberrations decreased through subsequent mitoses by approximately 60% in both FA and normal cells.

Hexokinase "New Hyde Park": a low activity erythrocyte isozyme in a Chinese kindred

Chronic hemolytic anemia in a 7-year-old Chinese boy was found to be associated with decreased activity of erythrocyte hexokinase (approximately 20% of appropriate control values). Alterations in kinetics, stability, pH optimum, or electrophoretic patterns could not be demonstrated with proband hexokinase, but subtle differences between maternal and paternal hexokinase characteristics suggested that two separate mutant isozymes were involved and that the proband was heterozygous for each. Comparisons with previously reported cases of hexokinase deficiency demonstrate the broad genetic heterogeneity that characterizes this disorder.

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.

[Enzyme deficiencies of blood cells in bone marrow insufficiency (author's transl]

Numerous enzyme defects-deficiency of pyruvate kinase, phosphofructo-kinase, glocosephosphate isomerase, adenylate kinase, 2,3-diphosphoglycerate mutase and glutathione reductase--in red blood cells have been described to be connected with dyserythropoietic or refractory anemias and panmyelopathies of different origin. These enzyme deficiencies also have been demonstrated in red cells of patients with acute leukemia. Most likely the enzyme deficiencies are acquired and are not important for the origin of anemia or bone marrow insufficiency. Partial derepression of fetal genes, qualitative and quantitative perturbations of genetic expression, and posttranslational variations of the enzyme protein by low molecular factors from plasma, erythrocytes or leukemic cells have been discussed as a reason of enzyme deficiency. The decrease of glutathione reductase deficiency is dependent of FAD deficiency.

Clinical and cytogenetic observations during a six-year period in an adult with Fanconi's anaemia

A male adult patient suffering from Fanconi's anemia is described who was diagnosed 5 years before the onset of clinical symptoms by cytogenetic findings of chromosomeinstability in a lymphocyte culture. Repeated clinical, haematological and biochemical investigations of the untreated patient have been made during the observation period of six years. In the same period of time cytogenetic studies have been carried out which show no correlation in results compared with the clinical or physical findings. Four well defined lymphocyte clones have been discovered. The patient is still under observation of the clinic and the cytogenetic department.

[Enzyme deficiencies in glycolysis and nucleotide metabolism of red blood cells in nonspherocytic hemolytic anemia (author's transl)]

The detection of enzyme deficiencies in glycolytic and nucleotide metabolism of human red blood cells has enriched the pathophysiological knowledge on the origin of nonspherocytic hemolytic anemias (NSHA). So far for 11 of 13 glycolytic enzymes deficiencies have been described which are connected with alterations of biochemical enzymatic properties. The most frequent enzyme deficiencies are those of GPI and PK. By performance of special electrophoretic techniques genetic studies allow the demonstration of homozygote and double heterozygote defect carriers. Up to now only adenylate kinase and pyrimidine 5' nucleotidase deficiencies have been detected as genetically determined in altered nucleotide metabolism. The metabolic alterations of several enzymopathies have been characterized so well, that the pathophysiological relations between enzyme deficiency and NSHA probably have been found to be a sufficient explanation.

Multiple neoplasms in two siblings with a variant form of Fanconi's anemia

Two siblings with a variant form of Fanconi's anemia developed multiple neoplasms after prolonged survival and treatment with androgens. One of the siblings developed two separate oral squamous cell carcinomata, and the other developed acute leukemia and hepatoma. Androgens may have had a carcinogenic role in the appearance of the hepatic neoplasm. There is an increased incidence of neoplasm associated with Fanconi's anemia. This may be related to frequent spontaneous chromosomal abberations and/or to increased cellular susceptibility to viral transformation.