Hemoglobin, alpha 2

Hemoglobin, alpha 2 also known as HBA2 is a gene that in humans codes for the alpha globin chain of hemoglobin.[5][6]

Available structures
PDBOrtholog search: PDBe RCSB
AliasesHBA2, HBA-T2, HBH, Hemoglobin, alpha 2, hemoglobin subunit alpha 2, ECYT7
External IDsOMIM: 141850 MGI: 96015 HomoloGene: 469 GeneCards: HBA2
Gene location (Human)
Chr.Chromosome 16 (human)[1]
Band16p13.3Start172,876 bp[1]
End173,710 bp[1]









RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 16: 0.17 – 0.17 MbChr 11: 32.28 – 32.28 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse


The human alpha globin gene cluster is located on chromosome 16 and spans about 30 kb, including seven alpha like globin genes and pseudogenes: 5'- HBZ - HBZP1 - HBM - HBAP1 - HBA2 - HBA1 - HBQ1 -3'. The HBA2 (α2) and HBA11) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions.


Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin.

Clinical significance

Alpha-thalassemias most commonly result from deletions of any of the four alpha alleles, although some alpha thalassemias have been reported that are due to mutations other than deletion. Deletion of 1 or 2 alleles is clinically silent. Deletion of 3 alleles causes HbH disease, resulting in anemia and hepatosplenomegaly. Deletion of all 4 alleles is lethal because it renders the body unable to make fetal hemoglobin (HbF), adult hemoglobin (HbA) or adult variant hemoglobin (HbA2), and results in hydrops fetalis.[7]


  1. GRCh38: Ensembl release 89: ENSG00000188536 - Ensembl, May 2017
  2. GRCm38: Ensembl release 89: ENSMUSG00000069919 - Ensembl, May 2017
  3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. Liebhaber SA, Goossens MJ, Kan YW (Dec 1980). "Cloning and complete nucleotide sequence of human 5'-alpha-globin gene". Proceedings of the National Academy of Sciences of the United States of America. 77 (12): 7054–8. doi:10.1073/pnas.77.12.7054. PMC 350439. PMID 6452630.
  6. Higgs DR, Vickers MA, Wilkie AO, Pretorius IM, Jarman AP, Weatherall DJ (Apr 1989). "A review of the molecular genetics of the human alpha-globin gene cluster". Blood. 73 (5): 1081–104. PMID 2649166.
  7. "Entrez Gene: HBA2 hemoglobin, alpha 2".

Further reading

  • Richter F, Meurers BH, Zhu C, Medvedeva VP, Chesselet MF (Aug 2009). "Neurons express hemoglobin alpha- and beta-chains in rat and human brains". The Journal of Comparative Neurology. 515 (5): 538–47. doi:10.1002/cne.22062. PMC 3123135. PMID 19479992.
  • Phylipsen M, Vogelaar IP, Schaap RA, Arkesteijn SG, Boxma GL, van Helden WC, Wildschut IC, de Bruin-Roest AC, Giordano PC, Harteveld CL (Aug 2010). "A new alpha(0)-thalassemia deletion found in a Dutch family (--(AW))". Blood Cells, Molecules & Diseases. 45 (2): 133–5. doi:10.1016/j.bcmd.2010.05.004. PMID 20682466.
  • Sessa R, Puzone S, Ammirabile M, Piscopo C, Pagano L, Colucci S, Izzo P, Grosso M (Feb 2010). "Identification and molecular characterization of the --CAMPANIA deletion, a novel alpha (0) -thalassemic defect, in two unrelated Italian families [corrected]". American Journal of Hematology. 85 (2): 143–4. doi:10.1002/ajh.21591. PMID 20054848.
  • Yin XL, Zhang XH, Zhou TH, Zhang TL, Luo RG, Wang L, Zhou YL, Chen YS, Kong XJ, Liang B, He YY, Peng L, Lu LB, Fang SP, Wu ZK (2010). "Hemoglobin H disease in Guangxi province, Southern China: clinical review of 357 patients". Acta Haematologica. 124 (2): 86–91. doi:10.1159/000314058. PMID 20639625.
  • Joly P, Lacan P, Bererd M, Garcia C, Zanella-Cleon I, Becchi M, Aubry M, Couprie N, Francina A (2009). "Description of two new alpha variants: Hb Canuts [alpha85(F6)Asp-->His (alpha1)] and Hb Ambroise Pare [alpha117(GH5)Phe-->Ile (alpha2)]; two new beta variants: Hb Beaujolais [beta84(EF8)Thr-->Asn] and Hb Monplaisir [beta147 (Tyr-Lys-Leu-Ala-Phe-Phe-Leu-Leu-Ser-Asn-Phe-Tyr-158-COOH)] and one new delta variant: Hb (A2)North Africa [delta59(E3)Lys-->Met]". Hemoglobin. 33 (3): 196–205. doi:10.1080/03630260903058685. PMID 19657833.
  • Harteveld CL, Oosterhuis WP, Schoenmakers CH, Ananta H, Kos S, Bakker Verweij M, van Delft P, Arkesteijn SG, Phylipsen M, Giordano PC (Apr 2010). "alpha-thalassaemia masked by beta gene defects and a new polyadenylation site mutation on the alpha2-globin gene". European Journal of Haematology. 84 (4): 354–8. doi:10.1111/j.1600-0609.2009.01380.x. PMID 19912309.
  • Kapralov A, Vlasova II, Feng W, Maeda A, Walson K, Tyurin VA, Huang Z, Aneja RK, Carcillo J, Bayir H, Kagan VE (Oct 2009). "Peroxidase activity of hemoglobin-haptoglobin complexes: covalent aggregation and oxidative stress in plasma and macrophages". The Journal of Biological Chemistry. 284 (44): 30395–407. doi:10.1074/jbc.M109.045567. PMC 2781594. PMID 19740759.
  • Roy P, Bhattacharya G, Banerjee D, Chandra S, Ghosh M, Choudhuri U, Das M, Dasgupta UB (2009). "Hb Sallanches [alpha104(G11)Cys-->Tyr, TGC>TAC] occurs frequently on the Indian subcontinent". Hemoglobin. 33 (6): 486–91. doi:10.3109/03630260903336164. PMID 19958194.
  • Giardina B, Messana I, Scatena R, Castagnola M (1995). "The multiple functions of hemoglobin". Critical Reviews in Biochemistry and Molecular Biology. 30 (3): 165–96. doi:10.3109/10409239509085142. PMID 7555018.
  • Higgs DR, Vickers MA, Wilkie AO, Pretorius IM, Jarman AP, Weatherall DJ (Apr 1989). "A review of the molecular genetics of the human alpha-globin gene cluster". Blood. 73 (5): 1081–104. PMID 2649166.
  • Ribeiro DM, Sonati MF (2008). "Regulation of human alpha-globin gene expression and alpha-thalassemia". Genetics and Molecular Research. 7 (4): 1045–53. doi:10.4238/vol7-4gmr472. PMID 19048483.
  • Waye JS, Eng B, Dutly F, Frischknecht H (2009). "alpha-Thalassemia caused by two novel splice mutations of the alpha2-globin gene: IVS-I-1 (G>A and G>T)". Hemoglobin. 33 (6): 519–22. doi:10.3109/03630260903333377. PMID 19958200.
  • Coelho A, Picanço I, Seuanes F, Seixas MT, Faustino P (Aug 2010). "Novel large deletions in the human alpha-globin gene cluster: Clarifying the HS-40 long-range regulatory role in the native chromosome environment" (PDF). Blood Cells, Molecules & Diseases. 45 (2): 147–53. doi:10.1016/j.bcmd.2010.05.010. PMID 20580289.
  • Sharma V, Kumar B, Kumar G, Saxena R (Oct 2009). "Alpha globin gene numbers: an important modifier of HbE/beta thalassemia". Hematology. 14 (5): 297–300. doi:10.1179/102453309X446126. PMID 19843387.
  • Turbpaiboon C, Wilairat P (2010). "Alpha-hemoglobin stabilizing protein: molecular function and clinical correlation". Frontiers in Bioscience. 15: 1–11. doi:10.2741/3601. PMID 20036801.
  • Voon HP, Vadolas J (Dec 2008). "Controlling alpha-globin: a review of alpha-globin expression and its impact on beta-thalassemia". Haematologica. 93 (12): 1868–76. doi:10.3324/haematol.13490. PMID 18768527.
  • Giordano PC, Cnossen MH, Joosten AM, Jansen CA, Hakvoort TE, Bakker-Verweij M, Arkesteijn SG, van Delft P, Waye JS, Bouva MJ, Harteveld CL (2010). "Codon 24 (TAT>TAG) and codon 32 (ATG>AGG) (Hb Rotterdam): two novel alpha2 gene mutations associated with mild alpha-thalassemia found in the same family after newborn screening". Hemoglobin. 34 (4): 354–65. doi:10.3109/03630269.2010.486341. PMID 20642333.
  • Mahdavi MR, Kowsarian M, Karami H, Mohseni A, Vahidshahi K, Roshan P, Hojjati MT, Ebrahimzadeh MA (Oct 2010). "Prevalence of hemoglobin alpha-chain gene deletion in neonates in North of Iran". European Review for Medical and Pharmacological Sciences. 14 (10): 871–5. PMID 21222374.
  • Balakrishnan G, Zhao X, Podstawska E, Proniewicz LM, Kincaid JR, Spiro TG (Apr 2009). "Subunit-selective interrogation of CO recombination in carbonmonoxy hemoglobin by isotope-edited time-resolved resonance Raman spectroscopy". Biochemistry. 48 (14): 3120–6. doi:10.1021/bi802190f. PMC 2722936. PMID 19245215.
  • Zhu C, Yu W, Xie J, Chen L, Ding H, Shang X, Xu X (Oct 2010). "Hemoglobin H disease due to a de novo mutation at the α2-globin gene and an inherited common α-thalassemia deletion found in a Chinese boy". Blood Cells, Molecules & Diseases. 45 (3): 223–6. doi:10.1016/j.bcmd.2010.07.005. PMID 20691621.

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