Relapsing hypocupraemic myelopathy requiring high-dose oral copper replacement.

Adult-onset copper deficiency with neurological manifestations is a newly recognised syndrome. Long-term oral copper replacement therapy has been the mainstay of treatment in the literature. A case of relapsing hypocupraemic myelopathy responsive to increased doses of copper replacement is reported. Standard doses of copper may not be sufficient for all patients.

Secondary iron overload disorders.

Diverse clinical disorders distinct from hereditary hemochromatosis are associated with accumulation of excess body iron in heterogeneous patterns and through various mechanisms. A deranged iron turnover somehow relates to the altered physiological barrier for iron absorption in several defined chronic anemias with ineffective erythropoiesis. Unexcretable excess iron acquired from transfusions provides a therapeutic challenge. Genetic defects of proteins essential for transport of iron into and out of cells (transferrin and ceruloplasmin) deprive the erythron of the metal and cause its accumulation in other vital organs. The hemochromatosis alleles predictably contribute to an iron burden from other causes, commonly facilitate the expression of porphyria cutanea tarda, and their clinical expression may be accelerated by hereditary hemolytic anemias. Even minimal iron excess in liver disease may contribute to the hepatocellular injury from factors such as alcohol and viruses. Uniquely localized siderosis occurs in the lung and kidney where iron cannot turn over and causes variable tissue damage. The most devastating iron overload disorder, neonatal hemochromatosis, is understood least of all.

CNS demyelination associated with copper deficiency and hyperzincemia.

CNS demyelination is not a previously reported feature of acquired copper deficiency. The authors report two patients with idiopathic hypocupremia and hyperzincemia, hematologic changes of copper deficiency, and extensive CNS demyelination. Hematologic recovery followed copper supplementation, both initially and after relapse off copper therapy, while serum zinc levels remained high and the neurologic abnormalities only stabilized.

Acute intermittent porphyria: novel missense mutations in the human hydroxymethylbilane synthase gene.

PURPOSE: To identify mutations in families with acute intermittent porphyria, an autosomal dominant inborn error of metabolism that results from the half-normal activity of the third enzyme in the heme biosynthetic pathway, hydroxymethylbilane synthase. METHODS: Mutations were identified by direct solid phase sequencing. RESULTS: Two novel missense mutations E80G and T78P and three previously reported mutations, R173W, G111R, and the splice site lesion, IVS1+1, were detected, each in an unrelated proband. The causality of the novel missense mutations was demonstrated by expression studies. CONCLUSION: These findings provide for the precise diagnosis of carriers in these families and further expand the molecular heterogeneity of AIP.

The diagnosis of acute intermittent porphyria. Usefulness and limitations of the erythrocyte uroporphyrinogen I synthase assay.

In acute intermittent porphyria (AIP) the inherited metabolic defect residues in a partial enzyme deficiency at the uroporphyrinogen I synthase (URO-S) step of heme biosynthesis. Assay of this enzyme in erythrocytes is increasingly used for diagnosis of the genetic defect. Erythrocyte URO-S activity was measured by three laboratories in members of 14 AIP kindreds and found helpful for diagnosing the asymptomatic carrier state, since activity of the enzyme was usually distributed bimodally. However, a definite diagnosis of the carrier state was not always possible with this assay: approximately 7% of a total of 340 determinations were inconclusive. Repeat enzyme assays, enzyme assays by more than one laboratory, quantitative urine porphobilinogen determinations, and studies of other family members all aided in arriving at a firm diagnosis for most of those in whom a single erythrocyte URO-S measurement was inconclusive. Because the enzyme is unstable, blood specimens should be stored frozen if immediate assay is not possible.

Pure red cell aplasia associated with fenoprofen.

A 69-year-old man developed pure red cell aplasia after taking fenoprofen for ten months. The erythroid defect fully reversed after the drug was discontinued and could not be attributed to the patient's previously treated lung carcinoma. This case represents the third example of erythroid aplasia associated with an anti-inflammatory agent and the first instance due to fenoprofen.

Iron deficiency due to excessive therapeutic phlebotomy in hemochromatosis.

Thirteen adults (eight men, five women) with hemochromatosis had undergone routine iron depletion therapy but while on maintenance phlebotomies developed iron deficiency which persisted for 25 +/- 13 (mean +/- 1 SD) months before diagnosis. All had symptoms and signs of iron deficiency. Levels of transferrin saturation were 10% +/- 5% (1 SD), and serum ferritin concentrations were 8 +/- 3 ng/mL. Eleven had anemia; eight had hypochromia and microcytosis. Bone marrow specimens obtained in five patients revealed no stainable iron. Medical records indicated that parameters of body iron status were infrequently or incorrectly used for adjusting the frequency of phlebotomies. Two patients developed iron deficiency due to additional blood loss from esophageal varices and bilateral hip replacement, respectively. Ten of the patients were treated with ferrous sulfate, 325 mg daily, for 2-6 weeks when anemia was corrected. In patients who were not given iron, anemia and microcytosis recovered in 8-24 months. We conclude that (i) sustained iron deficiency in hemochromatosis patients should be prevented by monitoring hemoglobin levels and serum ferritin; and (ii) hemoglobin concentrations and values of mean corpuscular hemoglobin may be higher in iron-deficient persons with hemochromatosis than in individuals without hemochromatosis. Symptomatic iron deficiency in hemochromatosis patients may be treated safely with a brief course of ferrous sulfate. Recovery is slower when iron is not given. However, iron supplementation is unnecessary and not recommended for the mild, self-limited anemia and decreased serum iron and ferritin concentrations encountered after initial iron depletion therapy for hemochromatosis.

A new chromosome abnormality in idiopathic sideroblastic anemia: 46,XY,del11q23.

A new marker chromosome, deletion 11q23, was observed with the Giemsa banding technique in the bone marrow of a patient with idiopathic sideroblastic anemia. The abnormality was not detectable in the peripheral blood or with nonbanded chromosome studies. Nineteen of 40 cases of this disorder studied and reported to date had chromosomal aberrations, although the majority had only nonbanded karyotypes performed. This apparently high incidence of chromosomal defects and the finding in the present case indicate that more banded-karyotype analyses are needed to assess the presence of possible nonrandom cytogenetic changes in idiopathic sideroblastic anemia.

Diminished erythroid ferrochelatase activity in protoporphyria.

In two patients with protoporphyria the enzymatic synthesis of aminolevulinic acid and prophobilinogen in erythroid tissue was normal. Boine marrow ferrochelatase activity was less than one-fourth of the mean activity in normal control subjects. Ferrochelatase activity in peripheral blood reticulocytes was less than 10% of controls. This metabolic abnormality provides one biochemical explanation for the increased concentrations of blood protoporphyrin in protoporphyria and clarifies the apparent minimally impaired hemoglobin synthesis in the two case studies.

Iron metabolism in K562 erythroleukemic cells.

Iron delivery to K562 cells is enhanced by desferrioxamine through induction of transferrin receptors. Experiments were performed to further characterize this event with respect to iron metabolism and heme synthesis. In control cells, up to 85% of the iron taken up from iron-transferrin was incorporated into ferritin, 7% into heme, and the remainder into compartments not yet identified. In cells grown with desferrioxamine, net accumulation of intracellular desferrioxamine (14-fold) was observed and iron incorporation into ferritin and heme was inhibited by 86% and 75%, respectively. In contrast, complete inhibition of heme synthesis in cells grown with succinylacetone had no effect on transferrin binding or iron uptake. Exogenous hemin (30 microM) inhibited transferrin binding and iron uptake by 70% and heme synthesis by 90%. These effects were already evident after 2 h. Thus, although heme production could be reduced by desferrioxamine, succinylacetone, and hemin, cell iron uptake was enhanced only by the intracellular iron chelator. The effects of exogenous heme are probably unphysiologic and the greater inhibition of iron flow into heme can be explained by effects on early steps of heme synthesis. We conclude that in this cell model a chelatable intracellular iron pool rather than heme synthesis mediates regulation of iron uptake.

Bone marrow delta-aminolaevulinate synthase deficiency in a female with congenital sideroblastic anemia.

Heme biosynthesis was examined in erythroid tissue of a 4-yr-old girl with severe sideroblastic anemia since infancy, as documented by the presence of intramitochondrial deposits of iron in erythroblasts. Free red cell protoporphyrin, urinary porphyrins, and activities of erythrocyte porphobilinogen synthase, uroporphyrinogen 1 synthase, aspartate aminotransferase, and pyridoxine kinase were normal or increased. Bone marrow ferrochelatase activity was normal. Activity of bone marrow delta-aminolaevulinate (ALA) synthase was markedly reduced to 7 pmole ALA/10(6) erythroblasts/30 min (normal 127 +/- 29) but was enhanced fivefold by pyridoxal phosphate (normal 0%--25% increase). Therapy with oral pyridoxine and parenteral pyridoxal-5'-phosphate did not increase effective red cell production. The sideroblastic anemia in this patient appears to be related to a congenital defect in the initial step of heme biosynthesis.

5-Aminolevulinate synthase in sideroblastic anemias: mRNA and enzyme activity levels in bone marrow cells.

To examine the role of 5-aminolevulinate synthase (ALAS) in the pathogenesis of sideroblastic anemias, levels of mRNAs for erythroid and housekeeping ALAS isozymes were examined, and total ALAS activity was assessed in bone marrow cells. In two patients with X-linked sideroblastic anemia the levels of mRNA for erythroid ALAS as well as for alpha and beta globin appear to be decreased while levels of mRNA for glycophorin A in both patients were the same as in normal individuals. However, amounts of housekeeping ALAS mRNA were increased two- to threefold in these patients. Total ALAS activity was also increased two- or threefold, perhaps reflecting increased transcription of the housekeeping gene in response to diminished cellular heme in erythroid cells and/or enhanced translation of the erythroid isoform in response to iron accumulation. In a third patient with X-linked sideroblastic anemia ALAS activity was low but increased to twice the normal value after pyridoxine administration, suggesting a structural defect of the enzyme. In a fourth patient, with isolated congenital, pyridoxine-responsive sideroblastic anemia, the erythroid ALAS mRNA was normal and a low enzyme activity was strikingly enhanced by pyridoxal-phosphate albeit to subnormal levels. In idiopathic acquired sideroblastic anemia, ALAS mRNA for both isozymes was normal and enzyme activity was slightly elevated. These observations thus reflect heterogeneous aberrations of erythroid heme synthesis in the various types of sideroblastic anemia and suggest that defects involving erythroid ALAS underlie at least some of them.

Sideroblastic anemia with markedly increased free erythrocyte protoporphyrin without dermal photosensitivity.

A patient with idiopathic sideroblastic anemia and atypical clinical and biochemical findings is described. He had a greatly increased erythrocyte and plasma protoporphyrin, but normal urine and fecal porphyrins. The erythrocyte protoporphyrin had a fluorescence spectrum typical of free protoporphyrin, but caused no photosensitivity. Bone marrow metal chelatase activity was normal. There were no clinical signs of liver disease. The abnormal porphyrin metabolism in this patient is not known though a number of explanations are discussed.