Pyridoxine-responsive primary acquired sideroblastic anaemia. In vitro and in vivo effects of vitamin B6 on decreased 5-aminolaevulinate synthase activity

Scand J Haematol. 1982 Nov;29(5):421-4.


The activity of 5-aminolaevulinate (ALA) synthase, the first and rate-limiting of haem synthesis, was markedly reduced (13% of controls) in erythroblasts of a patient with acquired, primary sideroblastic anaemia (PASA). The reduced activity of ALA synthase could not be restored in vitro with 1 mmol/l pyridoxal-5-phosphate (PLP). Treatment of the patient with pyridoxine for several months increased the ALA synthase activity from 13% to 50% of controls in the absence and to 100% in the presence of PLP in the incubation medium. These studies suggest that both increased degradation of apo-ALA synthase and decreased affinity of ALA synthase for PLP may be involved in pyridoxine-responsive PASA.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Aminolevulinate Synthetase / blood*
  • Adult
  • Aged
  • Anemia, Sideroblastic / drug therapy*
  • Erythroblasts / enzymology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pyridoxal Phosphate / pharmacology
  • Pyridoxine / pharmacology
  • Pyridoxine / therapeutic use*


  • Pyridoxal Phosphate
  • 5-Aminolevulinate Synthetase
  • Pyridoxine