For children at endline, lower levels of serum ferritin and soluble transferrin receptor as compared to baseline led to contrasting estimates of iron deficiency as measured by serum ferritin (12% vs. 21%) and soluble transferrin receptor (33% vs. 20%), but this change did not affect total body iron measures (baseline vs. endline means: 2.9 vs. 2.6 mg/kg; iron deficiency prevalence: 18% vs. 20%). The gene discussed is TFRC; the disease is Iron deficiency anemia.