The State of Piauí presented the highest frequency of newborns with heterozygosis for Hb S (FAS), which is important clinical information for identifying families at risk of generating children with sickle cell disease, followed by heterozygosis for Hb C (FAC) and Hb D (FAD), and homozygosis for Hb S (FS). Here, GSTM1 is linked to sickle cell disease.