3 March 2021 (Wednesday) - Where Is It?

 We had an interesting blood group today. Reacting rather weakly with one anti-D and hardly at all with another, was this a weak D or a D-fraction? This is something which is important to get right as one can make ant-D and one can’t. So… what is the difference? I found this article (click here to read it) which said:

"In partial D, the RhD proteins have amino acid changes outside of the membrane, whereas in weak D the RhD proteins have one or more amino acid substitutions within either the membranespanning domains or the cytoplasmic loops of the protein, but not externally exposed (Wagner et al, 1999; Flegel et al, 2007)”.  

A tad scientific perhaps, but a useful definition? However the very next sentence read:

One major flaw with this definition is that the precise locations of the amino acid residues of the RhD protein within the membrane are not known; different models predict different locations for some amino acids." 

How on Earth can you categorise something based on its location when you don’t know where it is?

Just how much else is like this? – A hard-and-fast definition based on nothing at all?

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