GATA1 and X-linked sideroblastic anemia 1: In vitro, CRISPR-mediated disruption of non-coding variants associated with X-linked sideroblastic anemia and pyruvate kinase deficiency revealed that even small (2–4 nt) changes in GATA1 binding sites reduce GATA1 binding and impair recruitment of cofactors like TAL1 [118].