Blood Bank: Rh Blood Group Review

Chromosome 1

The RHD and RHCE genes are located on…

Chromosome 6

RHAG gene is located on…

Rh associated glycoprotein

An ammonia transporter protein, similar in structure to the Rh proteins and within the RBC membrane forms complexes with the Rh polypeptides; must be present for expression of Rh Ag

Rh null hemolytic anemia (RHN) (Rh deficiency syndrome)

Defects in the RHAG gene would cause…

Haplotype

A set of DNA variations that are usually inherited together

Phenotype

Trait that is visible; physical test results from specific antisera

Genotype

Genetic makeup of an individual; is not visible; cannot be absolutely determine without family or DNA studies, but can be “inferred” from phenotyping, based on published frequency of genes in a population

Fisher-Race

(Rh nomenclature) genetic inheritance of 3 closely linked genes that produce Ags

Wiener

(Rh nomenclature) genetic inheritance of 1 gene that produces the Ags

Rosenfield

(Rh nomenclature) disregards genetics and assigns numbers to various Ags

ISBT

(Rh nomenclature) Disregards genetics and assigns numbers to the specific blood group and to its corresponding various Ags

• Rh₀

• rh’

• rh”

• hr’

• hr”

What are the 5 major Rh Ags (longhand) in Wiener nomenclature?

• R⁰ = Dce

• R¹ = DCe

• R² = DcE

• R^z = DCE

• r = ce

• r’ = Ce

• r” = cE

• r^y = CE

Describe the Weiner shorthand nomenclature (8)

• Rh1 = D

• Rh2 = C

• Rh3 = E

• Rh4 = c

• Rh5 = e

Describe the Rosenfield nomenclature (5)

D > c > E > C > e

List the Rh antigens from most to least immunogenic

• Cation transport

• Membrane integrity

• Regulates cell volume

List some functions that the Rh antigens have in the RBC membrane (3)

1. Weakened expression

2. Gene position effect

3. Mosaic effect (incomplete/partial D)

How can weak D Ag be inherited (3)

• African Americans

• 10,000-33,000

• 200-1,983

Weakened expression of D is more common in (——), where the normal number of epitopes is (——) but people with weakened expression of D have (——) epitopes

• trans

• Steric hindrance

• D positive

(Weak D) the gene position effect only occurs when the C allele is in (——) position to the D allele; (——) causes the anti-D reagent to weakly attach (C Ag crowds the D Ag); in this case, (——) blood can be given to the patient

RhCE

In incomplete/partial D, parts of RhD are replaced with (——)

• If anti-D negative at IS, pt cells and reagent incubated 37°C for 15 min, centrifuge, read reaction

• If negative, wash 3x, add AHG

  • If negative, add CC and report Rh neg

  • If positive, report weak D positive or D positive

Describe how to do the weak D/Du test (4)

Rh6 (f)

(cis product Ag) c and e inherited as a haplotype (cde or cDe)

Rh7 (rh_i)

(cis product Ag) C and e inherited as a haplotype

Rh27

(cis product Ag) c and E inherited as a haplotype

Rh22

(cis product Ag) C and E inherited as a haplotype

C or D

Genes that code for (—2—) also code for G; anti-G mimics anti (—2—), where one antibody cannot be separated from the other

C^w

Low frequency Ag found in only 2% of Caucasians and rare in African Americans; most individuals who are C+ are also positive for this; Abs to these Ags can be naturally occurring and may play a role in HDFN and HTR

• More common

• mutation in RHAG

• RHD and RHCE

• Rh_null

For the regulator type Rh deficiency, it is (——) than amorph type, and is caused by a (——); can transmit normal (——), and is designated as (——)

• Mutation in RHCE gene, deletion in RHD gene

• RHAG

• double bar over rr

For the amorph type Rh deficiency, it is caused by (——), (——) gene is normal, and is designated as (——)

Anti-Rh29 (anti-total Rh)

Rh_null individuals can form the antibody (——), which us why they must be transfused with other Rh_null blood

RHAG

Rh_mod inherited characteristic associated with severely reduced Rh Ag expression; involves a mutation in the (——) gene with partial suppression of Rh Ags; expression varies

• Transfusion or pregnancy

• anti-E and anti-C^w

Most Rh Abs occur from immunization due to (—2—), except for rare examples of (—2—) which may be naturally occurring

Extravascular destruction

Rh Abs do not bind C’; for C’ to be bound, 2 closely attached IgGs must exist, but Rh Ags are not close enough; Rh Abs “coat” the RBC which leads to (——)

R²R²

Of the following, which one reacts more strongly with anti-D due to higher density of D Ag on the cell? R¹R¹ or R²R²?

Anti-f

Generally weak reacting Ab that is found with other Abs; reacts when both c and e ags are present on the same haplotype (cis), e.g., rr; has been called the “compound" Ag”; transfuse c or e negative blood

Anti-G

Reacts to most D and C Ag positive cells; is most frequently developed in rr phenotypes; transfuse D and C negative blood

Anti-E

Most frequently encountered Ab followed by anti-c where anti-c can sometimes fall below detectable levels

Anti-e

Rarely encountered as only 2% of the population is ag negative'; some autoimmune diseases can create an Ab that shows this specificity

Anti-Rh17

Ab created in individuals found to be D deleted phenotypes (D- -)

High protein

(Rh antisera) IgG and anti-D potentiated with high percent of bovine albumin and other macro molecules to ensure agglutination at IS; causes false positives with RBCs coated with Abs, autoagglutinins, abnormal serum protein, Abs to additives, using unwashed RBCs; can be used for weak D test

Monoclonal anti-D

(Rh antisera) Prepared from blend of monoclonal IgM and polyclonal IgG suspended in a low percent of bovine albumin diluent (IgM react at IS, IgG at AHG (Du test)); most frequently used reagent; negative control not needed unless patient AB positive

Saline/low protein

(Rh antisera) Prepared from predominantly IgM Abs, scarce due to difficulty obtaining raw material; reserved for individuals giving false positives with high protein; require incubation at 37°C; cannot be used for weak D test

Chemically modified

(Rh antisera) IgG converted to saline agglutinin by weakening disulfide bonds at hinge region, greater flexibility, and increases span distance; stronger reactivity than IgM Abs; can be used for weak D; negative control unnecessary unless AB positive