A mutation in ALAS2 can result in a congenital sideroblastic anemia and can be lethal.

Chromosome: Xp11.21

Gene: ALAS2 (5'-aminolevulinate synthase 2)

Gene product: mitochrondrial protein that catalyzes the first step in the heme biosynthetic pathway


Inheritance: X-linked, predominantly affecting males. Females may be affected if the mutation causes X-linked dominant inheritance.


Clinical features:

(1) dyserythropoiesis with macrocytic and sideroblastic anemia and neutropenia, with some developing myelodysplasia

(2) iron overload

(3) variable response to pyridoxine (pyridoxal 5'-phosphatase is a cofactor essential for ALAS2 activity)

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