Individuals lost to follow up were younger (45.2 vs 49.4 years), were more likely to have high education (20.8% vs 10.9%, p<0.001), had higher Hb (13.6 vs 13.2 g/dl, p<0.001) and a lower prevalence of anemia (21.5% vs 30.7%, p<0.001), but there were no differences in mean BMI (p = 0.324), or energy (p = 0.246) and riboflavin intake (p = 0.358). The gene discussed is GSTM1; the disease is anemia.