However, II‐4, who is positive for –α3.7/‐‐SEA, shows the symptoms of HbH disease with RBC 5.38 × 1012, HGB 90 g/L, MCV 58.6 fl, MCH 16.7 pg, and MCHC 286 g/L. The gene discussed is CYGB; the disease is hemoglobin H disease.