Developmental Changes in Hb Globin Makeup
alpha-like beta-like
Embryonic
(<8 weeks) zeta2 -> zeta1 epsilon
Fetal
(8-41 weeks) alpha gammaG -> gammaA
Adult
(birth-death) alpha beta and (some) delta
For convenience, the different flavours are also referred to as 'zeta globin', 'gamma globin' and 'alpha-beta globin' (or simply unqualified 'h(a)emoglobin') respectively.