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Rbc ag typing by dna analysis


jalomahe

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These are the codes I was given several years ago.

Test Step

CPT Code / Description

Coding

Multiplier

Extraction

83891:

Isolation or extraction of highly purified nucleic acid X1

Amplification

83900:

Amplification of patient nucleic acid, multiplex; first two nucleic acid sequences X1

Amplification

83901:

Amplification of patient nucleic acid, multiplex each additional nucleic acid sequence X30

Enzymatic Digestion

(PCR Cleanup & Single Strand DNA Generation) 83892: Enzymatic digestion X2

Annealing/Elongation/

Imaging 83914:

Mutation I.D. by enzyme ligation or primer extension, single segment, each segment X32

Data Analysis/Report

83912:

Interpretation and report X1

The multiplier represents HEA version 1.2 which types for 32 blood group antigens.

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I'm going to be really pedantic here (not like me at all, I can hear everybody saying), but you cannot do red cell antigen typing by DNA.

What you can do is DNA work to see if a particular blood group antigen gene is present on the individuals genome, and from this you can predict that a certain antigen may be expressed on the red cells, but this is not always so.

We had a case last year where, phenotypically, the patient was quite clearly M-, but genotypically, apparently carried the MN1 gene, by "normal" DNA work. Thgis caused us all sorts of confusion, until some more esoteric DNA work was performed, and it turned out that the "normal" DNA work was detecting the (for want of a better way of putting it) MN1 gene at the GPE locus, rather than an MN1 gene at the GPA locus.

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I agree with Malcolm. DNA work can predict, but does not show if the antigen is expressed. To complicate things, does it matter regarding transfusion therapy. Do we provide "gene" compatible blood? This could decrease your donor pool. Additionally, it will be interesting to see how insurance companies will see paying for something more expensive when less expensive serological phenotyping is available and still meets patient needs. DNA work is interesting and can be a good tool for investigating the strange and unusual, but it may complicate things too much for routine testing and currently not licensed by FDA.

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I also agree with Malcom. Had a fetus supposedly typed D pos with DNA. (I don't remember how it was collected) The doc was all set to do an intrauterine transfusion, we had the blood ready. They sent the fetus blood sample to the BB to type and the fetus was Rh neg! No problems, no HDN.

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