Anti-Fy3

[NicolaHT]

Couldn't find the relevant forum in the UK bit, but any information would be grateful.

I wonder if anyone can help me with something.

I have a patient who has developed anti-Fya and anti-Fy3.

She was phenotyped as Fy(a-b-), but genotype performed at IBGRL stated Fya negative, Fyb positive, GATA mutation positive (homozygous).

I understand that due to the GATA mutation she would not express Fyb on her red cells, and so the phenotype would be correct, but would express it on other tissues so would not develop anti-Fyb. However, I thought that because she expressed Fyb on tissues that she couldn't develop anti-Fy3, because the Fy3 portion was part of the Fy structure.

Have I misunderstood this?

Thanks!

 

[Malcolm Needs ☆]

Hi NocolaBM,

There is no doubt that the individuals with the Fy(a-b-) phenotype, who have the FYB gene and are homozygous for the GATA-1 mutation very rarely produce an anti-Fy3, but every now and again, you may come across one who does.  I came across at least two examples of this when I was working in RCI at NHSBT-Tooting Centre.  Under the circumstances, I sent samples to the IBGRL for confirmation of both the antibody specificity, and the genotype.

Joyce Poole, who was, at the time, Head of Red Cell Serology at the IBGRL confirmed the specificity and the genotyping were both correct, but speculated that the antibody may have had a true specificity within the Duffy Blood Group System, but may, nevertheless, be mimicking an anti-Fy3.  She asked me to send her samples from any other such individuals, but I never came across another one myself and, due to the rarity of this situation, as far as I know, Joyce was never able to prove her theory prior to retiring.

I would love to claim, incidentally, that the above diagram was all my own work, but it ws not.  Sadly, and to my shame, I cannot now remember from where I copied it.

I attach a slide that Professor Dave Anstee gave me permission to use, which shows very nicely how the GATA-1 mutation works.

GATA1.pptx

[NicolaHT]

Thank you Malcolm. I read your reply on my night shift and then totally forgot to reply. 

I could find any literature relating to anti-Fy3 in those with the FYB gene, but I suppose half the reason we love this job is because not everything can be explained! 

Still, makes for a good case study! 

 

[Malcolm Needs ☆]

Not a problem in the least.