X-linked sideroblastic anaemia due to a mutation in the erythroid 5-aminolaevulinate synthase gene leading to an arginine170 to leucine substitution.

DNA sequencing of the coding region of the erythroid 5-aminolaevulinate synthase (ALAS2) cDNA from a male with pyridoxine-responsive sideroblastic anaemia revealed a missense mutation, a G561T transversion in exon 5 of the gene. Previously, the mutation G561A has been shown to be responsible for sideroblastic anaemia in females and thought to be lethal in males (1). The mutation G561T results in the loss of an MspA1-I cutting site.