GSTM1 and malaria: The difference in Hb level between asymptomatic subjects and those with clinical malaria was most pronounced in the young children with a maximum difference (median) in Hb level of 2.2 g/dl in children <2 years decreasing to 0.1 g/dl in those aged ≥15 years (12.1 g/dl versus 12.2 g/dl).