Haemoglobin structure, synthesis and developmental switching
The globin tetramer and its genes on chromosomes 11 and 16, the T and R states and 2,3-BPG binding, haem synthesis and how lead and sideroblastic anaemia break it, the fetal to adult switch and BCL11A, and how haemoglobin variants show up on the blood count, oximetry and HbA1c.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Haemoglobin is a tetramer of two alpha-like and two beta-like globin chains, each holding one haem with ferrous (Fe2+) iron. One gram carries 1.34 mL of oxygen.
- Alpha genes sit on chromosome 16; beta-like genes (epsilon, gamma, delta, beta) on chromosome 11, in the order they are switched on.
- Binding is cooperative. The switch between the T (tense, low affinity) and R (relaxed, high affinity) states gives the sigmoid dissociation curve.
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Sources
- Hoffbrand's Essential Haematology (8th ed.)Wiley-Blackwell (Hoffbrand and Steensma, 2019), 2019
- Postgraduate Haematology (7th ed.)Wiley-Blackwell (Hoffbrand, Higgs, Keeling and Mehta, 2016), 2016
- The switch from fetal to adult hemoglobinCold Spring Harbor Perspectives in Medicine (Sankaran and Orkin, 2013;3:a011643), 2013
- CRISPR-Cas9 gene editing for sickle cell disease and beta-thalassemiaNew England Journal of Medicine (Frangoul et al., 2021;384:252-260), 2021
- Exagamglogene autotemcel for severe sickle cell diseaseNew England Journal of Medicine (Frangoul et al., 2024;390:1649-1662), 2024
- Exagamglogene autotemcel for transfusion-dependent beta-thalassemiaNew England Journal of Medicine (Locatelli et al., 2024;390:1663-1676), 2024
- Information paper: evidence on the effects of lead on human healthAU/NZNational Health and Medical Research Council (2015), 2015
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Deploy to Cloudflare on push to main