We found that 8 patients (16.0%, all males; Table 1) had a Hb higher than the diagnostic threshold for erythrocytosis (≥165 g/L for men, ≥160 g/L for women).[41] The 30-year-old female patient with CN2 had a serum TB concentration of 186.2 μmmol/L, Hb of 153 g/L, and Ret of 3.44%. The gene discussed is GSTM1; the disease is polycythemia.