Medicina: Ematologia: Talassemie e trapianto del midollo osseo
| English |
| globin chain |
  |
|
| Attestation |
3
|
| Part of speech |
Noun syntagm
|
| Grammatical label |
Countable
|
| Definition |
a-globin chain: the normal human has two a genes on each chromosome 16. Each is responsible for 25% of the normal total a chain synthesis. Non-a globin chains: there is only one beta gene on each chromosome 11, and each contributes 50% of the output. The gene is part of a complex containing also the d and g genes. Globin chain synthesis must be balanced: the output of a and non-a chains must be equal. Both free a, and free b chains are toxic to the developing erythroblast. If a globin gene is missing, or if some aspect of the transcription or translation of the globin proteins is impaired, then imbalanced globin chain synthesis occurs. Complete loss of output from a single beta globin gene leads to a 50% reduction in synthesis of b globin chain. When both b genes fail, then there will be no b chain produced (and therefore no HbA). In contrast, complete loss of one a gene leads to a 25% loss of a globin output, two genes to 50%, three to 75%, and when all the a genes are missing, then no a chain is produced.
|
| Definition source |
Medicine Online. Medical Dictionary.
|
| Context |
The degree of globin chain imbalance is the major determinant of the severity of thalassemia syndromes. In b-thalassemia, indeed, the absent or reduced output of b-globin chains leads to a great excess of a-chains which precipitate causing damage to the cell membrane.
|
| Context source |
Cao, A., et al. (1994). ‘Genotype-phenoptype correlations in beta-thalassemias’. Blood Reviews 8(1):1-12. Review. (RISCEN85)
|
| Figure source |
http://www.people.virginia.edu/~rjh9u/hgb.html
|
| Synonym |
Globin
|
| Subject field |
Haemopoiesis
|
| Comprehensive concept |
Hemoglobin
|
| Specific concept |
a globin chain, b globin chain, d globin chain, g globin chain, e globin chain, z globin chain
|
| it |
Catena globinica
|
| Reliability code |
3
|
|
