When does switchover from fetal to adult hemoglobin synthesis begin -

Ans. is 'c' i.e., 36 weeks gestationFetal Hb (a272)Adults Hb (a2o During the initial fetal life, the major hemoglobin synthesized in the body is fetal hemoglobin, because in fetus, the chain synthesized predominantly is the 7 chain.13 chain is present in only trace amount in early embryosThe rate of synthesis of y and 13 chains and the amount of HbA and HbF are inversely related during intrauterine stage.o As the age of the fetus increases, the synthesis of 13 chains and the amount of adult hemoglobin in the blood increaseso At 36 weeks of gestational age the rate of synthesis of 13 chain exceeds that of y chain. This is called switch over.