The Hb, HbA2, MCV, and MCH of ‐‐SEA/αα were lower than ‐α3.7/αα and ‐α4.2/αα in the three common deletional genotypes, suggesting that the severity of anemia depends on the number of inactivated α‐globin genes. The gene discussed is GSTM1; the disease is anemia (phenotype).