Instead of histidine 143, histidine is replaced with serene. And serene, as we know, does not have a positive charge. So serine is neutral. And what that means is in the pocket of fetal hemoglobin there is a smaller positive charge because these two histidines histidine 143 on this subunit and HistoGene 143 on this subunit are replaced with serene. And so instead of having a positive sit charge we essentially have a positive four charge, a smaller positive charge. Now, what is the physiological consequence of that?