More recently, for families with unexplained microcytic hypochromic anemia and elevated HbA2, or with unexplained β-thalassemia intermedia phenotypes, whole genome sequencing (WGS) analysis revealed the involvement of a hitherto unsuspected trans-acting factor (Spt5) encoded by SUPT5H, which, when haplo-insufficient, reduced β-globin gene expression (Achour et al., 2020). Here, SUPT5H is linked to anemia.