Anemia is a condition in which the number of red blood cells (RBCs) or the Hb concentration within them is lower than normal.5 Anemia may produce clinical symptoms, such as fatigue, palpitations, headache, and shortness of breath, and signs, such as conjunctival and palmar pallor, which in spite of having low sensitivity and moderate specificity to diagnose anemia,6 are still useful when laboratory assessment is limited.7,8 In clinical practice and in public health, the measurement of Hb concentration is the most common indicator and assessment method used to define anemia. Here, GSTM1 is linked to anemia (phenotype).