BCL11A and Schnyder corneal dystrophy: Some studies have used CRISPR–Cas9 to introduce HPFH‐related point mutations into erythrocytes, disrupt the γ‐globin gene promoter, inhibit BCL11A and ZBTB7A/LRF binding to the γ‐globin gene promoter, induce and enhance γ‐globin gene expression, improve the HbF level, and effectively improve the clinical symptoms of SCD.219