10 April 1997

Dear Hum-molgen subscribers,

I have a doubt about the composition of the haemoglobin molecule in some special circumstances.

1.- Individual with heterozygous status for Haemoglobin A and Haemoglobin S (Sickle cell trait). As we known, the haemoglobin molecule is made up of 2 alpha chains plus 2 beta chains. In the case referred to above, is it possible to find hemoglobin molecules constructed of 2 alpha chains plus 1 normal-beta chain and 1 mutant(S)-beta chain, or must the haemoglobin molecules in those individuals be constructed of 2 alpha chains plus 2 normal-beta chains, and 2 alpha chains and 2 mutant(S)-beta chains?

2.- Foetal haemoglobin is made up of 2 alpha chains and two gamma chains. As we know, there are two gamma chains in each chromosome 11; they code for gamma chains differing in the aminoacid #136: glycine versus alanine. The question is: Can we find foetal haemoglobin molecules composed of 2 alpha chains plus 1 gamma-G chain and 1 gamma-A chain, or must foetal haemoglobin molecules be constructed of 2 alpha chains plus 2 gamma-G chains, and 2 alpha chains plus 2 gamma-A chains?

Sorry to bother you with this, but any help would be welcomed.

Thanks in advance.