The epsilon globin gene (HBE) is normally expressed in the embryonic yolk sac: two epsilon chains together with two zeta chains (an alpha-like globin) constitute the embryonic hemoglobin Hb Gower I; two epsilon chains together with two alpha chains form the embryonic Hb Gower II. Both of these embryonic hemoglobins are normally supplanted by fetal, and later, adult hemoglobin. The five beta-like globin genes are found within a 45 kb cluster on chromosome 11 in the following order: 5' - epsilon – gamma-G – gamma-A – delta – beta - 3'.[6]
Gelinas R, Endlich B, Pfeiffer C, et al. (1985). "G to A substitution in the distal CCAAT box of the A gamma-globin gene in Greek hereditary persistence of fetal haemoglobin". Nature. 313 (6000): 323–5. Bibcode:1985Natur.313..323G. doi:10.1038/313323a0. PMID2578619. S2CID4353948.
Chabot B, Black DL, LeMaster DM, Steitz JA (1986). "The 3' splice site of pre-messenger RNA is recognized by a small nuclear ribonucleoprotein". Science. 230 (4732): 1344–9. doi:10.1126/science.2933810. PMID2933810.
Fei YJ, Stoming TA, Efremov GD, et al. (1988). "Beta-thalassemia due to a T----A mutation within the ATA box". Biochem. Biophys. Res. Commun. 153 (2): 741–7. doi:10.1016/S0006-291X(88)81157-4. PMID3382401.
Ruskin B, Greene JM, Green MR (1985). "Cryptic branch point activation allows accurate in vitro splicing of human beta-globin intron mutants". Cell. 41 (3): 833–44. doi:10.1016/S0092-8674(85)80064-7. PMID3879973. S2CID41979452.