To help determine the accuracy of Hb measurements of capillary blood and of anemia diagnoses among toddlers and pregnant women based on these measurements, we compared Hb values (and corresponding anemia status determinations) based on analyses of capillary samples with portable hemoglobinometers to reference Hb values (and corresponding anemia status determinations) based on analyses of venous blood with Coulter Counters. The gene discussed is GSTM1; the disease is anemia (phenotype).