However, in the most recent South African Demographic and Health Survey (SADHS) conducted in 2016 [23], anaemia prevalence rates were reported based on altitude-adjusted Hb values, while previous national surveys, such as the 2012 South African National Health and Nutrition Examination Survey (SANHANES) [24], reported unadjusted values. Here, GSTM1 is linked to anemia (phenotype).