In this longitudinal study of children in Ontario, where NBS carrier results for hemoglobinopathy mutations (i.e., Hb AS, Hb AC, Hb AD, Hb AE) are not disclosed to families by default, children who were carriers of such mutations did not consistently use health services at different rates than matched population controls who screened negative. Here, GSTM1 is linked to hemoglobinopathy.