Sideroblastic Anaemia in Man: Observations on Seventy Cases

Lack of efficacy of pyridoxine (vitamin B6) treatment in acquired idiopathic sideroblastic anaemia, including refractory anaemia with ring sideroblasts

Pyridoxine, or vitamin B6, is commonly used to treat acquired idiopathic sideroblastic anaemia (AISA, including refractory anaemia with ring sideroblasts), but the efficacy of this therapy in an unselected AISA population (i.e. patients without confirmed ALAS2 or other pyridoxine-responsive germline mutations) has not been established. We reviewed clinical data from 231 patients with AISA and found that 42% of 203 evaluable patients had been treated with pyridoxine. Only 6.8% of pyridoxine-treated patients experienced a haemoglobin improvement (≥ 1.5 g/dL) meeting 2006 International Working Group for Myelodysplastic Syndromes standardised response criteria. As some patients received combination therapy with erythropoietin or other agents, improvement could be attributed to pyridoxine monotherapy in only one patient (1.4%). Smaller, less meaningful increments in haemoglobin levels of 0.5 g/dL were observed in 13.5% of patients. Response to therapy did not correlate with International Prognostic Scoring System (IPSS) risk group or multilineage vs unilineage dysplasia. New symptomatic peripheral neuropathy was noted in 2.3% of patients treated with pyridoxine. In this large series of unselected patients with sideroblastic anaemia, pyridoxine therapy was ineffective and was associated with a risk of adverse effects. Pyridoxine therapy should be reserved for patients with known or suspected pyridoxine-responsive mutations.

Myelodysplastic patients with raised percentage of hypochromic red cells have evidence of functional iron deficiency

Raised percentage hypochromic red cells (%HRC) were detected at diagnosis in 10 of 34 consecutive patients with low-risk myelodysplastic syndrome (MDS) [refractory anemia (RA) (4/26) and RA with ring sideroblasts (6/8)], all of whom had normal or increased serum ferritin and bone marrow iron stores. Elevated %HRC has persisted in all 10 cases and subsequently developed in another RA patient who later had a complete remission of MDS with normalisation of %HRC after a respiratory tract infection. A strong positive correlation was found between %HRC and erythrocyte zinc protoporphyrin levels in 11 MDS patients tested (p=0.01), suggesting that functional iron deficiency contributes to ineffective erythropoiesis in cases of MDS with raised %HRC. Five of seven patients with elevated %HRC had satisfactory haemoglobin responses to a trial of human recombinant erythropoietin without iron supplementation.

Sir John Dacie MD, FRS, FRCP, FRCPath

Prof. Sir John Dacie was one of the most distinguished haematologists of the 20th century. He died on 12 February 2005 at the age of 92. This annotation is intended to give an impression of his career, and his role in the development of haematology in the UK and beyond. It describes his approach to haematological practise, taking account of both clinical and laboratory aspects, and reviews his published works over a range of haematological topics.

Remission of transfusion-dependent myelodysplastic syndrome in association with respiratory tract infection

We describe a case of blood transfusion-dependent myelodysplastic syndrome (refractory anaemia), associated with macrocytosis and elevated percentage of hypochromic cells. Following an acute hospital admission with a respiratory tract infection, the patient entered a complete and sustained remission.

Reversible sideroblastic anemia associated with the tetracycline analogue COL-3

Eight of 35 patients with cancer receiving COL-3, a tetracycline derivative with antiangiogenic properties, developed anemia while on treatment. All of these patients were enrolled on an approved Phase I clinical trial at the National Cancer Institute. Three of these patients had bone marrow examinations that revealed ringed sideroblasts. This paper describes these cases. Am. J. Hematol. 67:51-53, 2001. Published 2001 Wiley-Liss, Inc.

Phase I clinical trial of oral COL-3, a matrix metalloproteinase inhibitor, in patients with refractory metastatic cancer

PURPOSE

This phase I clinical trial was designed to determine the maximum-tolerated dose and dose-limiting toxicities of the matrix metalloproteinase (MMP) inhibitor COL-3 in patients with refractory solid tumors.

PATIENTS AND METHODS

Thirty-five patients with different cancer types were enrolled. COL-3 doses were escalated from 36 mg/m2/d in successive cohorts of at least three patients. Circulating levels of MMP-2, MMP-9, vascular endothelial growth factor, and basic fibroblast growth factor were assessed during treatment. Pharmacokinetic parameters were assessed for single and multiple doses of drug.

RESULTS

Cutaneous phototoxicity was dose-limiting at 98 mg/m2/d. With the use of prophylactic sunblock, COL-3 was well tolerated at 70 mg/m2/d. The dose of 36 mg/m2/d was well tolerated without the use of sunblock. Other toxicities that did not seem to be related to dose or pharmacokinetics included anemia, anorexia, constipation, dizziness, elevated liver function test results, fever, headache, heartburn, nausea, vomiting, peripheral and central neurotoxicities, fatigue, and three cases of drug-induced lupus. Disease stabilization for periods of 26+ months, 8 months, and 6 months were seen in hemangioendothelioma, Sertoli-Leydig cell tumor, and fibrosarcoma, respectively. There was a potentially statistically significant relationship between changes in plasma MMP-2 levels and cumulative doses of drug when progressive disease patients were compared with those with stable disease or toxicity (P = .042).

CONCLUSION

COL-3 induced disease stabilization in several patients who had a nonepithelial type of malignancy. Phototoxicity was dose-limiting. We recommend the dose of 36 mg/m2/d for phase II trials.

Refractory anemia with ringed sideroblasts in children: two diseases with a similar phenotype?

Three pediatric patients with refractory anemia with ringed sideroblasts (RARS) are presented. Bone marrow aspirates were examined using Romanowsky and Prussian blue iron stains in all three patients, and electron microscopic analysis was performed in one patient. All three patients had cytogenetic analysis of the bone marrow. Other studies included analysis of serum iron, total iron-binding capacity, ferritin, copper, vitamins B6 and B12, and folate levels. Antibody titers to Parvovirus, HIV, and other viruses were measured. The patients had contrasting clinical courses. Patients 1 and 2 had dysplastic hematopoietic features and cytogenetic findings (with either partial or one allele loss of chromosome 7), suggestive of myelodysplastic syndrome. Patient 1 experienced acute myeloid leukemia (AML) and had a good response to AML-directed therapy. Patient 2 had prolonged cytopenias and underwent bone marrow transplantation (BMT). Patient 3 had features suggestive of refractory anemia associated with mitochondrial cytopathy, including normal cytogenetics with pronounced vacuolization of marrow precursors. His anemia regressed spontaneously a few months after diagnosis. These patients represent two subgroups of pediatric RARS. Patients with the myelodysplastic syndrome (MDS) type may progress to cytopenias or leukemia and may require aggressive therapy; the type is characterized by clonal cytogenetic findings. The non-MDS type, which may relate to mitochondrial cytopathy, often shows spontaneous regression and requires only supportive treatment; it has normal cytogenetic findings.

Late-onset X-linked sideroblastic anemia. Missense mutations in the erythroid delta-aminolevulinate synthase (ALAS2) gene in two pyridoxine-responsive patients initially diagnosed with acquired refractory anemia and ringed sideroblasts

X-linked sideroblastic anemia (XLSA) is caused by mutations of the erythroid-specific delta-aminolevulinate synthase gene (ALAS2) resulting in deficient heme synthesis. The characteristic hypochromic, microcytic anemia typically becomes manifest in the first three decades of life. Hematologic response to pyridoxine is variable and rarely complete. We report two unrelated cases of highly pyridoxine-responsive XLSA in geriatric patients previously diagnosed with refractory anemia and ringed sideroblasts. A previously unaffected 77-yr-old male and an 81-yr-old female were each found to have developed severe hypochromic, microcytic anemia with ringed sideroblasts in the bone marrow, which responded dramatically to pyridoxine with normalization of hemoglobin values. Sequence analysis identified an A to C transversion in exon 7 (K299Q) of the ALAS2 gene in the male proband and his daughter. In the female proband a G to A transition was identified in exon 5 (A172T). This mutation resulted in decreased in vitro stability of bone marrow delta-aminolevulinate synthase activity. Each patient's recombinant mutant ALAS2 enzyme had marked thermolability. Addition of pyridoxal 5'-phosphate in vitro stabilized the mutant enzymes, consistent with the observed dramatic response to pyridoxine in vivo. This late-onset form of XLSA can be distinguished from refractory anemia and ringed sideroblasts by microcytosis, pyridoxine-responsiveness, and ALAS2 mutations. These findings emphasize the need to consider all elderly patients with microcytic sideroblastic anemia as candidates for XLSA, especially if pyridoxine responsiveness is demonstrated.

Growth hormone deficiency and empty sella in DIDMOAD syndrome: an endocrine study

Two girls with DIDMOAD syndrome are presented. One also had severe megaloblastic-sideroblastic anaemia and the other several neurological manifestations. Both were short with defective growth hormone secretion. Computed tomography revealed empty sella in both girls; one had widespread atrophic cortical and cerebellar changes. High doses of thiamine improved the anaemia in the first case, increased C peptide secretion in both, but had no effect on the neurological abnormalities.

The pathogenesis of anemia in rheumatoid arthritis: a clinical and laboratory analysis

Principal concepts concerning the anemia of RA are summarized in Tables 7 and 8. These concepts have been validated by our analysis of 93 anemic RA patients and by our review of the literature. The fact that anemia in RA may have one or more etiologies, occasionally in the same patient, mandates a reasoned approach to the analysis of anemia in every RA patient in whom it may occur. In particular, iron deficiency is common and determination of bone marrow iron content via an aspirate may be required for a definitive diagnosis. In those RA patients with anemia of chronic disease, the best therapy remains control of the underlying disease, most commonly with second line drugs and/or corticosteroids. The place for recombinant erythropoietin in the therapy of this anemia has not been defined; one specific role for erythropoietin may be in the preparation of RA patients for elective surgery, particularly hip arthroplasty, where correction of the anemia may either obviate the need for transfusion or may allow for donation of blood for purposes of autologous transfusion perioperatively. The pathogenesis of the anemia of chronic disease, as seen in RA anemia, is not completely understood. Inflammatory mediators, particularly the cytokines, appear to be important factors in the impairment of erythropoiesis. The mechanism by which these cytokines impair erythroid progenitor growth and hemoglobin production in developing erythrocytes is an important area for future study.

Anaemia in rheumatoid arthritis: pathogenesis, diagnosis and treatment

The pathogenesis, diagnosis and treatment of the anaemia of chronic disorders (ACD) in rheumatoid arthritis (RA) were reviewed. Causes of anaemia other than ACD frequently present in RA. Decreased iron absorption was shown to be the result of active RA rather than a cause of ACD or iron deficiency. It has been hypothesized that bone marrow iron availability decreases due to decreased iron release by the mononuclear phagocyte system or that the anaemia in ACD is due to ineffective erythropoiesis; these remain controversial theories. Studies considering a decreased erythropoietin responsiveness have not produced consistent results. Erythroid colony growth is suppressed in vitro by interleukins and tumour necrosis factor but their role in vivo in ACD is unknown. The diagnosis of ACD is made by exclusion. Iron deficiency is detected by transferrin, ferritin, and cellular indices after adaptation of their normal values. Treatment of the anaemia consists merely of antirheumatic treatment. Iron administration is counterproductive since iron chelators or exogenous erythropoietin administration might increase erythropoiesis.

Thiamine-responsive anemia in DIDMOAD syndrome

Two children with the DIDMOAD syndrome (diabetes insipidus, diabetes mellitus, optic atrophy, deafness) developed a megaloblastic and sideroblastic anemia, neutropenia, and borderline thrombocytopenia. Plasma thiamine concentration was low in one patient and normal in the other; in both children, thiamine pyrophosphate in erythrocytes and thiamine pyrophosphokinase activity were lower than the lowest values observed in control subjects. A month after institution of treatment with thiamine, the hematologic findings had returned to normal and the insulin requirements had decreased. Withdrawal of thiamine repeatedly induced relapse of the anemia and an increase in insulin requirements. We propose that an inherited abnormality of thiamine metabolism is responsible for the multisystem degenerative disorder known as DIDMOAD syndrome.

Busulfan-induced sideroblastic anemia

Patients in the stable phase of chronic myelogenous leukemia (CML) are usually treated with busulfan. The bone marrow of patients with CML may be exquisitely sensitive to busulfan, and occasionally such patients develop pancytopenia, secondary to hypoplasia or aplasia of the bone marrow, which is presumed to be due to busulfan-induced marrow toxicity. We report a case of Philadelphia chromosome-positive CML who developed pancytopenia while being treated with busulfan; however, the patient's bone marrow was not hypoplastic or aplastic but rather hyperplastic with sideroblastic changes. Busulfan is not known to cause sideroblastic changes, so this was considered to herald a transformation into acute leukemia. Busulfan was stopped, and only supportive treatment was given. To our surprise approximately 22 weeks after busulfan was stopped, the sideroblastic changes had disappeared and the bone marrow again showed features of CML. This case suggests that busulfan may cause sideroblastic anemia.

Management of myelodysplastic syndromes

The treatment of myelodysplastic syndromes is reviewed, with emphasis on recently published clinical trials. Pyridoxine is rarely effective, but a trial in patients with refractory anemia with ringed sideroblasts is justifiable. Corticosteroids do not appear indicated unless in vitro data suggest response. Androgens are generally not beneficial, although danazol merits further evaluation. Both 13-cis-retinoic acid and low-dose cytosine arabinoside have considerable toxicity and yield short-lived partial responses that may not have a significant impact on survival. Combination chemotherapy may be considered in selected patients with refractory anemia with excess of blasts, refractory anemia with excess of blasts in transformation, and chronic myelomonocytic leukemia; however, in general, its toxicity outweighs potential benefit. For unusual patients under 30 years old, bone marrow transplantation should be considered as first-line therapy. Until more effective and less toxic agents are available, supportive care may still be the most appropriate therapy for many of these generally elderly patients.

Sideroachrestic anemia with iron loading: treatment with desferrioxamine

A case of nontransfusion-dependent sideroachrestic anemia (SA) with hemosiderosis is described that showed significant improvement of hemosiderosis and fibrosis of the liver following treatment with desferrioxamine. The anemia, although not transfusion dependent, did not allow continued therapy with phlebotomies. Following the removal of about 16 g iron over 4.5 years, normalization of serum ferritin and reversal of fibrosis of the liver were observed. Management problems and the prognostic implications of desferrioxamine therapy are discussed.

Diabetes mellitus, thiamine-dependent megaloblastic anemia, and sensorineural deafness associated with deficient alpha-ketoglutarate dehydrogenase activity

Three brothers with diabetes mellitus, thiamine-responsive megaloblastic anemia, and sensorineural deafness are reported. Two had, in addition, congenital septal defects. The activities of thiamine-dependent enzymes were determined in one patient, revealing low alpha-ketoglutarate dehydrogenase activity, which could have caused a sideroblastic anemia with secondary megaloblastic changes. The anemia was thiamine dependent. The cause of the diabetes mellitus was not known, but it was not type 1.

Primary acquired sideroblastic anaemia and myeloproliferative disease: a report on three cases

Three patients who presented with primary acquired sideroblastic anaemia (PASA) later developed myelofibrosis (MF). As both are clonal disorders a second mutation is suggested.

Idiopathic refractory sideroachrestic anemia (IRSA) progressing to acute mixed lymphoblastic-myelomonoblastic leukemia. Case report and review of the literature

A longitudinal observation of a patient with idiopathic refractory sideroachrestic anemia (IRSA) progressing to acute mixed lymphoblastic-myelomonoblastic leukemia is reported. The leukemia was characterized by morphology, immunological cell markers, and dissociated clinical responsiveness to vincristine/prednisone and arabinosylcytosine/6-thioguanine. Attention is paid to the hematological changes prior to leukemia development. Acute leukemia was best heralded in this patient by a severe deterioration of dyserythropoiesis and by an increase of blasts in the marrow to more than 5%. The observed preleukemic features are compared to those described in the literature.

Anaemia in patients with myelomatosis

Twenty-four untreated patients with myelomatosis were studied in order to characterize their anaemia, using standard haematological and ferrokinetic techniques, together with measurements of circulating erythropoietin, erythropoietin sensitivity of marrow cultures and in vitro measurements of haem synthesis. There is a reduction in total erythroid output by the marrow, together with a minor degree of plasma expansion. In patients with normal renal function there is an appropriate increase in erythropoietin in response to anaemia, but in a few cases there may be reduced response of CFU-E to the hormone in vitro. No abnormality of iron status or haem synthesis was found. One case of folate deficiency was discovered.

Sideroblastic anaemia. A review of seven paediatric cases

Sideroblastic Anaemias are characterised by a) chronic hypochromic anemia, b) ringed sideroblasts in the bone marrow, c) an increase in total body iron, d) ineffective erythropoiesis and e) often abnormal concentrations of F.E.P. A classification of Sideroblastic Anaemia is given and the pathophysiology of Sideroblastic Anaemia is discussed. A series of seven paediatric cases with Sideroblastic Anaemia is presented and the results of studies of the iron, vitamin B6 and porphyrin metabolism are discussed. In two cases arguments for an ALA-synthetase deficiency are given. All five males were diagnosed as hereditary X-linked Sideroblastic Anaemia, one female as I.R.S.A. and the other female, who showed the features of the X-linked type, as congenital Sideroblastic Anaemia.

Sideroblastic anemia associated wtih hairy cell leukemia

A patient with leukemic reticuloendotheliosis ("hairy cell" leukemia) with sideroblastic anemia and an epinephrine-induced platelet-aggregation abnormality is presented. Immunologic membrane marker studies supported a B-lymphocyte origin of the hairy cells. It is hypothesized that a defect in the pluripotent marrow stem cell may be responsible for the hairy cell leukemia and for the intrinsic abnormalities in erythrocytes and platelets.

Deoxyuridine-suppression test and bone marrow culture for the diagnosis of macrocytic refractory anaemias

Deoxyuridine (dU) suppression test and granulocyte macrophage colony forming unit (CFU-GM) assay were performed, along with morphological analysis, vitamin B12 and folate assays, in 22 cases of macrocytic anaemia corresponding to various types of idiopathic dysmyelopoietic syndromes. The dU suppressive effect was found to be normal in 19 cases, and slightly subnormal in 3 cases. The parallel study of the in vitro bone marrow growth showed, except in cases of primary acquired sideroblastic anaemia, a reduced number of colonies associated with a relative increase of the cluster formation. Consequently, these two parallel functional studies can support a formal diagnosis of potentially preleukaemic myelodysplasia, whatever may be the morphological pattern and even in cases of marked macrocytic anaemias and secondary epiphenomenal folate or vitamin B12 deficiency.

Erythremia with special reference to sideroblastic anemia

An autopsy case of erythremia with sideroblastic tumor cell proliferation is described. A 60-year-old man was admitted to the hospital due to general fatigue and anorexia. Bone marrow aspiration revealed abnormalities in erythropoiesis (megaloblasts, 4%; sideroblasts, 84%; ring-formed, 39%, and PAS-positive, 5%). Therapy was directed to pulmonary tuberculosis. Anemia was not improved despite repeated whole blood and platelet transfusions. Serum iron and percentage saturation of the total iron-binding capacity rose during the course. Administration of vitamin B12, B6 or folic acid was inefffective. INAH was replaced by its derivative, IHMS, during the course, but the population of sideroblasts especially of ring-sideroblasts was invariably large (78%-100% and 39%-65% for total sideroblasts and ring-sideroblasts, respectively). He died with increasing abdominal pain and jaundice after three months' hospitalization. Main autopsy findings were: diffuse proliferation of atypical erythroblasts in the bone marrow, systemic lymph nodes, liver, spleen and kidneys. Most of the cells positively stained with iron. Tuberculosis of lungs with cavity formation. Discussion is focussed on the relationship between erythremia and sideroblastic anemia.

Aplastic anaemia: an analysis of 174 patients

The authors summarize their experience with 174 patients with aplastic anaemia (AA) with particular reference to course, prognostic factors, conversion to other blood disorders, treatment and outcome. Aplastic anaemia was defined as pancytopenia and a hypocellular marrow at some time during the illness. Seven patients terminated with acute leukaemia, 8 developed haematological features of sideroblastic anaemia and 5 showed a red cell membrane defect commonly found in paroxysmal noctural haemoglobinuria. Complete recovery occurred in only 4 patients; 70 others showed a partial remission with some residual haematological abnormality in peripheral blood. Eighteen of these had spontaneous remission. Remission was brief in 27 patients who died; only 32 patients remained in partial remission. Twenty-five per cent. of the patients with AA run an acute course and die within 6 months of the time of diagnosis. The remainder run a subacute or chronic course, punctuated in some cases by a transient remission, but in others by a conversion to other related haematological disorders. An acute course is suggested by a rapid onset of symptoms, a falling neutrophil count, a haemoglobin level less than 5 g/dl and a very low platelet count. A chronic course is likely in those patients who have a slow onset of symptoms, a stable neutrophil count and a Hb level in excess of 5 g/dl. The authors' experience shows that the disease runs either of the 2 courses irrespective of the supportive therapy.

A new syndrome of refractory sideroblastic anemia with vacuolization of marrow precursors and exocrine pancreatic dysfunction

In the past decade, we have studied four unrelated children with what we believe is a previously unreported disorder affecting the bone marrow and exocrine pancreas. During infancy these patients had the onset of severe, transfusion-dependent, macrocytic anemia plus a variable degree of neutropenia and thrombocytopenia. Their bone marrows had normal cellularity but were characterized by remarkable vacuolization of erythroid and myeloid precursors, hemosiderosis, and ringed sideroblasts. The vacuoles probably represented manifestations of cellular degeneration and death. In two patients, in vitro bone marrow cultures showed abnormal erythroid and myeloid progenitor cell growth and, in one child, abnormal vacuolated erythroid colonies. Family histories were unrevealing, parents were hematologically normal, and both sexes were involved. There was no evidence of specific nutritional deficiencies or exposure to agents associated with marrow vacuolization. A number of therapeutic interventions produced no effect. One child had clinical malabsorption. This child and one other had extensive pancreatic fibrosis at autopsy. The other two patients had findings indicating exocrine pancreatic dysfunction. Two children had splenic atrophy. This new syndrome, with associated bone marrow and exocrine pancreatic dysfunctions, differs in several respects from the syndrome of pancreatic liposis and neutropenia described by Shwachman et all and Bodian et al, and from other conditions with vacuolization of the marrow or sideroblastosis.

Sézary syndrome associated with sideroblastic anaemia

A 66-year-old man with acquired sideroblastic anaemia and Sézary syndrome is described. This is believed to be the first such case reported in the literature. We speculate on the possibility that a common stem cell defect could account for the simultaneous development of the two abnormalities. Other features of this case of Sézary syndrome are discussed in relation to previous reports on patients with this disease.

Iron overload despite partial gastrectomy

Iron overload was found in 3 patients who had undergone partial gastrectomy: a 61-year-old woman developed iron overload because she may have had idiopathic haemochromatosis and had also been given parenteral iron; in a 62-year-old man with thalassaemia minor, iron overload may have developed because of increased oral iron ingestion, low serum folate, increased, albeit ineffective, erythropoiesis and sideroblastic anaemia; a 74-year-old man with thalassaemia minor developed iron overload without exogenous therapy and died from a hepatoma. These cases illustrate that partial gastrectomy fails to protect patients from developing iron overload, particularly if given uncontrolled iron therapy.

Idiopathic refractory sideroblastic anemia: incidence and risk factors for leukemic transformation

The clinical course of 29 patients with idiopathic refractory sideroblastic anemia studied by us was reviewed. Four patients developed acute leukemia. We were able to find 27 out of 268 cases of idiopathic refractory sideroblastic anemia reported in the literature which terminated in acute leukemia. Nine of these were well described. The overall incidence of acute leukemia is 10%. In an attempt to identify the risk factors for the development of acute leukemia, the clinical and laboratory features of this group of thirteen well-described cases which terminated in acute leukemia were compared to the remaining 25 of our cases which did not undergo leukemic transformation. The patients who died of acute leukemia tended to have a more severe anemia, a lower reticulocyte count, and increased transfusion requirement, and thrombocytopenia. Thrombocytosis appears to be a relatively good prognostic sign.

Leukemia in patients with acquired idiopathic sideroblastic anemia: an evaluation of prognostic indicators

The initial clinical and laboratory data of 25 patients with acquired idiopathic sideroblastic anemia (AISA) were analyzed. Criteria for accepting the diagnosis were hyperferremia, ringed marrow sideroblasts, ineffective erythropoiesis, and exclusion of associated hematologic disorders. The findings of a mean age at onset of 70 years, increased mean corpuscular volume, relative neutropenia; and occasional splenomegaly at diagnosis corresponded with previous reports. During the followup for a median period of 32 months, 6 patients (25%) transformed to acute myelogenous or myelomonocytic leukemia after widely variable intervals. The initial data base of these patients was compared to that of the remaining 19 patients in order to isolate predictive features. Only a lesser degree of hyperferremia (P less than 0.001) made the group going on to leukemia distinctive. The median survival of these patients was 20 months. The median survival of 19 patients not developing leukemia was 72 months for males and 42 months for females. Hemochromatosis was diagnosed in four patients and was a primary or associated cause of death in three. Analysis of the transfusion history suggested that intrinsic iron leading was a major factor in these patients. We conclude that leukemic transformation in AISA is a common, poorly predictable event which required lengthy followup for detection. Hemochromatosis in AISA occurs frequently and shortens the median survival.

Vitamin B6 metabolism in idiopathic sideroblastic anaemia and related disorders

Patients with idiopathic anaemias associated with abnormal sideroblasts were defined according to morphologic and ferrokinetic criteria and the haematologic and biochemical effects of vitamin B6 therapy were evaluated. While all patients presented similar clinical pictures, peripheral blood changes and bone marrow abnormalities, two distinct groups were identified by sideroblast morphology and ferrokinetics. Patients with more than 5% true ring sideroblasts in the marrow (IRSA) uniformly had marked ineffective erythropoiesis, while those with abnormal sideroblasts but few true ring forms were hypoproliferative. Measurements of red cell pyridoxine kinase (PnK) and intracellular pyridoxal 5-phosphate availability (PLP) as assessed by the activity of the PLP-dependent enzyme asparate aminotransferase (EGOT), revealed slightly decreased PnK levels in IRSA subjects but normal intracellular PLP activities in both groups. Furthermore, when treated with pyridoxine, all patients showed increases in both red cell PnK and EGOT activities which were similar to those seen in normal subjects. Treatment with PLP also effectively increased erythrocyte vitamin B6 activity. Even so, neither pyridoxine nor intramuscular PLP improved erythropoiesis as determined by serial haematocrits, reticulocyte counts and erythron iron turnover measurements.However, since both therapies increased red cell protoporphyrin levels and the excretion of urinary coproporphyrin in a number of subjects, the possibility that impaired haem synthesis in the sideroblastic anaemias is associated with abnormal vitamin B6 metabolism at the level of the mitochondrion must still be considered.

Haem synthesis in sideroblastic anaemia

Measurement of delta-aminolaevulinic acid (ALA) synthetase has been performed in bone marrow of 24 normal subjects and 20 patients with sideroblastic anaemia (five congenital, two pyridoxine-responsive, 12 primary acquired and one secondary form due to isoniazid therapy). ALA-synthetase activity without added pyridoxal-phosphate in vitro was decreased in four of the congenital cases, and in all 12 primary acquired cases. In two of these 16 cases with low ALA-synthetase activity and in a case with sideroblastic change secondary to isoniazid therapy, the enzyme activity was corrected to normal by pyridoxal-phosphate in vitro. ALA-synthetase activity was normal in both cases of pyridoxine-responsive anaemia while they were receiving pyridoxine therapy but in one of these cases, studied at repeated intervals after withdrawal of pyridoxine therapy, the bone marrow ALA-synthetase activity fell to very low levels unless pyridoxal-phosphate was added in vitro. In this case the Km of the enzyme for pyridoxal-phosphate was substantially greater than that of a control sample. Haem synthetase activity was reduced in the bone marrow of two of six cases of primary acquired sideroblastic anaemia and in one congenital case tested but was normal in the pyridoxine-responsive patient studied on pyridoxine therapy. Nevertheless, this patient showed reduced incorporation of 14C-labelled delta-aminolaevulinic acid into bone marrow haem. It is concluded that both congenital and primary acquired sideroblastic anaemia are a heterogenous group of disorders, with different defects in haem synthesis, reduced activity of delta-aminolaevulinic acid synthetase being common but not invariable in both types. Pyridoxine-responsive (congenital) sideroblastic anaemia may be due to the presence of an abnormal ALA-synthetase apoenzyme which requires excessive amounts of the coenzyme, pyridoxal-phosphate, to achieve normal activity; other abnormalities of haem synthesis may also be present.

Thiamine-responsive megaloblastic anemia, sensorineural deafness, and diabetes mellitus: A new syndrome?

A 6-year-old girl is described who has congenital megaloblastic anemia which completely responded only to pharmacologic doses of thiamine. Relapse was observed twice when the drug was discontinued. The reintroduction of thiamine caused a prompt reticulocytosis and a rise in hemoglobin concentration. Other abnormalities included latent diabetes mellitus, sensorineural deafness, and "situs inversus totalis." Her parents are first cousins, both with partial deafness. Her father has an abnormal oral glucose tolerance test. A single similar case has been reported; the combination of almost the same anomalies seems to represent a newly recognized syndrome. This case reinforces the proposal that thiamine has a role in hematopoesis.

Deoxyuridine suppression studies in bone marrow in primary refractory sideroblastic anemia

Because unexplained megaloblastic erythroid maturation occurs in patients with primary refractory sideroblastic anemia (PRSA), deoxyuridine (dU) suppression tests using 125I-UdR were performed on bone marrow from five patients with PRSA. All patients had megaloblastic alterations in the marrow erythroid precursors (with normal serum folate and B12 levels) and numerous ringed sideroblasts, and most had marrow iron overload. Results of the dU suppression tests were normal in all five, both with and without incubation with pharmacologic amounts of folate, B12, and pyridoxal phosphate with or without 1-serine. Despite occasional hematologic improvement subsequent to folate, pyridoxine, or pyridoxal phosphate (PLP) administration in some patients with PRSA, normal dU suppression implies that in our group the availability of B12 and folate (and possibly PLP) was not limiting in the utilization of folate for DNA-thymine synthesis. The marrow erythroid maturation defect remains unexplained.

Serum pyridoxal and folate concentrations in diabetics

Serum pyridoxal and folate concentrations were measured in 518 diabetics. There were 185 males and 333 females. The level of pyridoxal was significantly lower in the diabetics when compared with 371 'healthy' controls and 25% had levels below the lower limit of the normal range. No significant difference was observed between diabetics being treated by diet alone, oral hypoglycaemics or insulin. Only 20 patients had a reduced serum folate level and in 6 this was accompanied by a low pyridoxal concentration. The results suggest that diabetics may have an increased demand for pyridoxal.

Sideroblastic and megaloblastic change

A case of primary sideroblastic anaemia is described in which megaloblastic changes in the bone marrow were found to be due to coincidental pernicious anaemia.

The importance is stressed of investigating all cases of macrocytic anaemia by iron staining of the marrow together with estimation of the serum B₁₂ and folate levels.