Abstract
Synthesis of human haemoglobin is directed by α-, β-, δ-, Glyγ- and Alaγ-genes. The switch from fetal to adult erythropoiesis includes a genetically controlled suppression of the γ- and activation of the β- and δ-chain synthesis. The two γ-genes are not equally inactivated. In animals external influences on the switch could be demonstrated, but no influence of extrauterine (EU) life on the switch in human newborns could be clearly demonstrated. The long half life of red cells hampers the detection of subtle influences on the switch by comparing the concentrations of HbA, HbF and HbA2. We studied therefor the de-novo synthesis of α-, β-, Alaγ- and Glyγ chains by measuring the incorporation of 3H-Leuctne into reticulocytes and subsequent separation of the globin chains by HPLC. 228 single measurements were obtained from 88 newborns (gestational age 26.3 to 42.1 weeks) at the age of 0 to 116 days; 16 babies were studied longitudinally. The results show that the switch γ→β is governed by the biological age (BA = intrauterine + EU age). A significant acceleration of the switch by EU life could be demonstrated: 1. The BA when 16 babies reached 50% (33%) of the full switch was not constant but correlated with GA: p<0.01 (p<0.05). 2. When 31 babies were studied at a BA of 40 to 43 weeks, a significant (p<0.02) acceleration of the switch was found in those with an EU age of 6 to 7 weeks (47%±21%, n=14) when compared to babies of 1 week ,or less of EU age (37%±25%, n=14). No comparable changes of the Alaγ/Glyγ-pattern was observed during the observation time of 26 to 43 weeks.
Conclusion: γ→β-switch is accelerated by factors of EU life.Inactivation pattern of Alaγ/Glyγ is not concerted with the γ→β-switch.
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Juchschmid, P., Frlschknecht, H., Schubiger, G. et al. 141 ACCELERATION OF THE SWITCH FROM FETAL TO ADULT HAEMOGLOBIN SYNTHESIS BY EXTRAUTERINE LIFE IN HUMAN NEWBORN INFANTS. Pediatr Res 28, 300 (1990). https://doi.org/10.1203/00006450-199009000-00165
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DOI: https://doi.org/10.1203/00006450-199009000-00165