Among the patients, the most frequently mutated genes were ALAS2 (n = 10; 23·3%) and SLC25A38 (n = 8; 18·6%), causing isolated forms of microcytic anaemia of varying severity.
Mutations in the erythroid-specific ALA synthase 2 (ALAS2) gene cause microcytic anemia, whereas mitochondrial DNA deletions are responsible for Pearsons syndrome with a macrocytic anemia.