Sideroblasts

X-linked sideroblastic anemia is not a porphyria but is included here because 6-aminolevulinic acid synthase is involved. 

Anderson KE et al Disorders of heme biosynthesis X-linked sideroblastic anemia and the porphyrias. In The Metabolic and Molecular Bases of Inherited Disease, 8th ed. Scriver CR et al (editors). McGraw-Hill, 2001. 

Pyridoxine (B ) Pyridoxal-P (PLP) Aminotransferases (transaminase) AST (GOT), ALT (GPT) 8-Aminolevulinate synthase Protein catabolism Heme synthesis MCC isoniazid therapy Sideroblastic anemia Cheilosis or stomatitis (cracking or scaling of lip borders and corners of the mouth) Convulsions... 

ALA synthase, the rate-limiting enzyme, requires pyridoxine (vitamin B ). Deficiency of pyri-doxine is associated with isoniazid therapy for tuberculosis and may cause sideroblastic anemia with ringed sideroblasts. 

Lead inactivates many enzjnnes including ALA dehydrase and ferrochelatase (hetne synthase), and can produce a microcytic sideroblastic anemia with ringed sideroblasts in the bone marrow. Other symptoms include ... 

Answer D. Sideroblastic anemia in a person being treated for tuberculosis (with isoni-azid) is most likely due to vitamin deficiency. 6-Aminolevulinate synthase, the first enzyme in heme synthesis requires vitamin Bj (pyridoxine). 

Adverse reactions may include the following Fever porphyria dysuria gout hepatic reaction nausea vomiting anorexia thrombocytopenia and sideroblastic anemia with erythroid hyperplasia vacuolation of erythrocytes increased serum iron concentration adverse effects on blood clotting mechanisms mild arthralgia and myalgia hypersensitivity reactions including rashes, urticaria, pruritus fever acne photosensitivity porphyria dysuria interstitial nephritis. 

Anemia Administration has been associated in a few cases with vitamin B-12 or folic acid deficiency, megaloblastic anemia, and sideroblastic anemia. If evidence of anemia develops, institute appropriate studies and therapy. 

Hypochromic and microcytic cells Iron deficiency Sideroblastic anaemia Thalassaemia and haemoglobinopathy... 

Pyridoxine vitamin Bf) deficiency symptoms are generally expressed as alterations in the skin, blood, and central nervous system. Symptoms include sensory neuritis, mental depression, and convulsions. Hypochromic, sideroblastic anemia also may result. Since pyridoxine is required for the conversion of tryptophan to diphos-phopyridine and triphosphopyridine nucleotides, pellagralike symptoms can occur with vitamin Bg deficiency. This deficiency is found most often in conjunction with other B complex deficiencies. 

Different classifications of anemia are based in part on the pathophysiological factor inducing the decreased hemoglobin concentration. Anemias due to cell hy-poproliferation include aplastic anemia and iron deficiency anemia. Hemolytic anemia results from excessive destruction of red blood cells. Megaloblastic anemia, sideroblastic anemia, and iron deficiency anemia result from an abnormality in the maturation of red blood cells. 

Sideroblastic anemia is characterized by excessive iron in the cells that cannot be incorporated into porphyrin to form heme. Although it is rare, the most common cause of sideroblastic anemia is alcoholism and pyridoxine deficiency. Pyridoxine is required for the formation of pyri-doxal phosphate, a coenzyme in porphyrin synthesis. 

Pearson syndrome [24] A refractory sideroblastic anemia, with variable neutropenia and thrombocytopenia, vacuolization of marrow precursors, and exocrine pancreatic dysfunction. Severe transfusion-dependent macrocytic anemia begins in early infancy (before 1 year) and the disease is fatal before 3 years in 62% of cases. Large-scale heteroplasmic deletions/duplications of mtDNA are constantly observed in affected and nonaffected organs. 

Sideroblastic anemia j Aarskog-Scott syndrome PGK deficiency hemolytic anemia... 

Androgens also have been used in the management and treatment of agnogenic myeloid metaplasia, aplastic anemia, breast cancer, hereditary angiodema, osteoporosis, paroxysmal nocturnal hemoglobinuria, and sideroblastic anemia. 

Anemia may result from other complications even when iron supply is sufficient. A decrease in hemoglobin synthesis, a fault in transport mechanisms or destruction of erythrocytes have all been noted. Sideroblastic or iron-loading anemias are characterized by a fault in iron metabolism (see Section 62.2.3.2). There are also several other syndromes of iron deficiency known clinically, including pica and Goodpasture s syndrome (an immune-related lung and kidney disease). The different categories of anemia have been discussed in detail by Prasad.48... 

Iron loading of mitochondria is observed in sideroblastic anemia in both animals and man (for review, see Ref. 69). The prototype of this... 

Sideroblastic defect (abnormal production of red blood cells), for example hereditary sideroblastic anaemia, acquired sideroblastic anaemia, including lead poisoning, and reversible sideroblastic anaemia. 

Characterised by sideroblastic anaemia and exocrine pancreas dysfunction. Usually fatal in infancy. The few patients who survive into adulthood often develop symptoms of Kearns-Sayre syndrome. It is very rare less than 100 cases have been reported. 

Sideroblastic anemia 8-Aminolevulinate synthase (1 heme synthesis) 2.3.1.37... 

As shown in Table 9.4, vitamin Be dependency has been reported in cases of type I primary hyperoxaluria, xanthurenic aciduria, homocystinuria, hypochromic sideroblastic anemia, gyrate atrophy with ornithinemia, and vitamin Be responsive infantile convulsions. In this last condition, the underlying defect has not been identified, but is almost certainly not impaired activity of glutamate decarboxylase. 

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