The risk of anaemia in this group that is considered likely to lead to blood transfusion (Hb < 5 g/dL) was very rare (≤ 1/10,000) if baseline haemoglobin concentration was ≥ 10 g/dL, rare (between 1/1000 and 1/10,000) for baseline haemoglobin of 9 g/dL, and uncommon for baseline haemoglobin 8 g/dL, compared to very rare for haemoglobin ≥ 9 g/dL and rare for haemoglobin of 8 g/dL in the no primaquine group. Here, GSTM1 is linked to anemia (phenotype).