GSTM1 and parasitic infectious disease: From a population point of view, determining socioeconomic conditions, the prevalence of parasitic infections (including malaria prevalence), genetic Hb variants that affect Hb concentrations, nutritional status of the population, wasting and stunting prevalence, infant mortality, food consumption patterns, environmental pollution (indoor cooking and lead exposure in particular), and water and sanitation conditions could help identify the origin of anemia.