SbbPerson

Hope this helps.
The P1PK Blood Group System.pptx

It simply means that the P1 antigen is particularly strongly expressed on these red cell samples.  Therefore, if you come across a weak anti-P1, it may apparently react with these particular red cell samples, whilst apparently not with, for example, the third red cell sample shown in your antigram.  Although not identical to dosage, per se, it is fairly synonymous with dosage at a phenotypical level.
The strength of the expression of the P1 antigen is an inherited trait.

or mum is a surrogate
or baby is the result of an ivf with external donors

 

"Sure it could happen ,,, and here's how... one of the parents perhaps has the Bombay phenotype" 

"Sure it could happen ,,, and here's how... one of the parents perhaps has the Bombay phenotype" 

"Sure it could happen ,,, and here's how... one of the parents perhaps has the Bombay phenotype" 

I'm chuckling reading all of this because it's like the question, 'If the parents are both Group O, can they produce a Group A baby?'
Ask a student, they'll say 'No way!'.
Ask a BB fanatic, they'll say, 'Sure it could happen ... and here's how ...'
And in this forum, there is never a simple answer!

Not in the UK.

I disagree. Most gel cards and Anti-D reagents won't detect DVI for patients. Fortunately I can find numerous suitable quotes, because it's true. 
 

 
 
https://labs-inc.org/pdf/361_3.pdf
 

I disagree. Most gel cards and Anti-D reagents won't detect DVI for patients. Fortunately I can find numerous suitable quotes, because it's true. 
 

 
 
https://labs-inc.org/pdf/361_3.pdf
 

I disagree. Most gel cards and Anti-D reagents won't detect DVI for patients. Fortunately I can find numerous suitable quotes, because it's true. 
 

 
 
https://labs-inc.org/pdf/361_3.pdf
 

Yes, but DVI donors need to be typed as D+.  Donors are not patients.

I agree.  The answer provided is vague in the extreme, and of little or no use to students who are at a basic level.  At that stage in their lives, the "model answer" provided would serve to confuse, rather than explain.

Sadly, I can't open the attachment of the answer.  I was hoping to see what was considered "critical thinking".  From the responses of others it would appear I am not missing much.  
Carry on folks.

Hope this works for you John, but you are correct; you were not missing much!

Yes, I don't think the original question setter meant the question to be a difficult one to answer. He is teaching a beginner level MLT course. He said there was only one correct "straight forward" answer. Just my opinion , but I think this person has no business teaching college level blood banking. As far as I know, he is a MLT with no experience with the tube, slide, or microplate testing methods, so I highly doubt he was talking about Anti-D reagents being the source of the discrepancy. But I could be wrong.
I apologize for wasting people's time with this. I just can't understand how is he teaching medical lab science and blood banking at a local college, and handing out assignments with these sort of questions.   
 
 

I have ABSOLUTELY no doubt that there is more than one answer!  That having been said, the Crawford antigen is encoded by the RHCE gene, specifically RHCE*ceCF (I'm sure you knew this already - but for those who didn't), and is not D Positive (for anyone interested in a damn good read, see Flegel WA, Wagner FF, Chen Q, Schlanser G, Frame T, Westhoff CM, Moulds MK.  The RHCE allele ceCF: the molecular basis of Crawford (RH43).  Transfusion 2006; 46: 1334-1342.  doi: 10.1111/j.1537-2995.2006.00901.x.).

I sincerely hope not David.  If this was donor blood, they most certainly SHOULD use an anti-D reagent that detects a Partial DVI, as such individual's have been known to stimulate the production of anti-D.  If it was a patient, then I would agree with you.

The donor could be a DVI but the blood center is testing using an anti-D that does not detect that epitope  (usually the hospital transfusion service doesn't want to find that person as Rh+ but the donor center does).  OR, the blood center has typed the incorrect unit.

Not sure about just one answer - We had a labeled Rh negative RBC from the ARC that retyped as Rh positive.  Upon investigation, it was found the Immucor anti-D reagent we use for retyping had anti-Crawford while the ARC automated process for D typing used an Ortho reagent which was from a different clone.  Not very unlikely but certainly more than one answer.    

Please don't apologise; I found your question (your question - not the question) quite stimulating.  I totally agree with your opinion re the question setter.

Yes, I don't think the original question setter meant the question to be a difficult one to answer. He is teaching a beginner level MLT course. He said there was only one correct "straight forward" answer. Just my opinion , but I think this person has no business teaching college level blood banking. As far as I know, he is a MLT with no experience with the tube, slide, or microplate testing methods, so I highly doubt he was talking about Anti-D reagents being the source of the discrepancy. But I could be wrong.
I apologize for wasting people's time with this. I just can't understand how is he teaching medical lab science and blood banking at a local college, and handing out assignments with these sort of questions.   
 
 

Thanks, but I would almost guarantee the original question setter hadn't read either of the two papers that I cited!

Malcolm's answer seems reasonable but I'm with you that all the original question does for me is lead to more questions and no answer.  Such as; what does "Investigation of the label issued at the blood bank verified the unit's correct labeling." actually mean??  Was this a real case or just something someone made up?

Perhaps the monoclonal anti-D reagents had been taken out of the fridge, and not allowed to come to room temperature before being used.  Most, if not all, monoclonal anti-D grouping reagents will detect an I-like or i-like antigen on D Negative red cells (see Thorpe SJ, Boult CE, Stevenson FK, Scott ML, Sutherland J, Spellerberg MB, Natvig JB, Thompson KM.  Cold agglutinin activity is common among human monoclonal IgM Rh system antibodies using the V4-34 heavy chain variable gene segment.  Transfusion 1997; 37: 1111-1116, and Thorpe SJ, Ball C, Fox B, Thompson KM, Thorpe R, Bristow A.  Anti-D and anti-i activities are inseparable in V4-34-encoded monoclonal anti-D: the same framework 1 residues are required for both activities.  Transfusion 2008; 48: 930-940).
What it should NOT be, under any circumstances, is that the anti-D reagents at the Central Blood Bank fails to detect an epitope that is detected by the hospital's anti-D reagent.