Patients with 2p15-16.1 microdeletions display depleted BCL11A expression in erythroblasts and markedly increased fetal γ-globin in peripheral blood. (A) Schematic of the 2p15-16.1 region showing segments that are deleted in the 3 patients. In addition to BCL11A, the following deleted genes are expressed at 1 or more stages during erythroid maturation:²⁵  VRK2, FANCL, PAPOLG, REL, PUS10, PEX13, KIAA1841, C2orf74, AHSA2, USP34, XPO1, FAM161A, CCT4, COMMD1, and B3GNT2. (B) Real-time reverse transcription-polymerase chain reaction quantification of BCL11A mRNA isoforms in erythroblasts expanded in vivo derived from patients (n = 3) and matched parents (n = 5). Shown are total BCL11A transcripts, isoforms previously implicated in γ-globin repression (BCL11A-XL and BCL11A-L) and short variants (BCL11A-S). All levels have been normalized to GAPDH mRNA. Error bars represent standard deviation and P values signify analysis of variation comparison. (C) HPLC determination of hemoglobin tetramer levels for the 3 patients and their parents. HbF peaks are shown in red. Note that HbA₂ (α₂δ₂) levels are relatively constant across all samples (2.3%, 2.6%, and 1.6% for the patients, and 2.2%, 2.8% and 2.6%, 2.4% and 2.2%, respectively, for the parents).