D partials and weaks Flashcards
4 groups of altered D
- Weak D 2. Partial D 3. Del 4. Nonfunctional RhD
Weak D
SNPs affect the intracellular domain of the antigen- epitopes not different but ability to place protein in membrane is altered hence low level of expression
Weak D types 1-3
not at risk for making anti-D (90% of weak D types for European ancestry)
Most common Weak D type and mutation
Weak D type one Valine270Glycine
How many weak D types are there
135
Ceppelini affect
C in Trans, C on opposite haplotype to D weakens the expression of D, this occurs in r’ phenotype
General rule for antibody production in partial D’s
can make anti-D antibody when exposed. Most partial D’s are hybrid genes with a recombination of RhD and RhCE, some partials are due to multiple nucleotide changes
DVI new antigen
BARC antigen
Rhnull gene nomenclature
RHD*01N non-functioning RhD gene that do not encode full length polypeptide
Del
10-30% D negative Asians, antigen can only be detected by elution studies due to faulty transplantation into RBC membrane, due to multiple different RhD mutation. Most associated with r’ phenotype
DHAR population
european
Crawford population
<0.1% blacks
What phenotypes (2) can show strong reactive positive results with certain monoclonal reagents but are negative with others
Crawford and DHAR - both lack expression of ‘conventional’ D and can be sensitized to D
Elevated D:
Rare deletion phenotypes D- - D c -, Dcw- , increased expression of D; no/altered or weak expression of C/c, E/e antigens. Hybrid D antigen, RhCE portions being replaced by RhD gene
D negative percentages per population
W-15% B 8% A (<0.1%)
DHAR positive with what reagents?
Almost all anti-sera except Orthobioclone and polyclonal
Crawford positive with what reagents?
negative with all reagents except positive with gammaclone (albuclone?)
D negative in europeans
most common D negative is a deletion of entire gene- homozygous for this trait
D Psuedogene
in a.a. 37 b.p. insertion into RhD results in a premature stop codon, no functional protein made
DVI variant
can make anti-D this is a partial D, very severe HDFN. not detected on bench typically needs a weak D test in order to pick up. Most common partial D in europeans.
anti-D reagents composed of:
IgM anti-D to detect at IS, IgG anti-D to detect Weak D during weak D testing. “blended reagent”
anti-D column agglutionation
only contains IgM** cannot detect Weak D positive
Weak D types 11 and 15
have been shown to make anti-D when exposed. All other types (besides 1-3) we are unsure of the potential of alloimmunization.
African american two most common Partial D’s
DIIIa and DAR, both typically test strong positive with anti-D though they can be alloimmunized and often are not recognized as variants until they make the antibody.
