More than 95% people in our study had mild symptoms, including mild anemia (Hb: 9-11 g/dl) and normal or moderately elevated serum ferritin level (<500 μg/L) However, there were still some people with severe anemia, elevated total bilirubin, enlarged spleen size, accompanied with iron overload and other complications (less than 5%). Here, GSTM1 is linked to Tangier disease.