Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Hillyer > Part III Pretransfusion Testing and Blood Group Antigens > Flashcards

Part III Pretransfusion Testing and Blood Group Antigens Flashcards

1
Q

More than 1/3 SCD patients with apparent C+ phenotype make anti-C or anti-Ce, because:

A

They do not have a conventional RhCe protein; the C antigen is expressed from a hybrid RHD gene that has lost expression of D, but encodes a C epitope. These patients are better served on C- rather than C+ transfusion protocols.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Does ACOG recommend the use of RhIG in patients with weak expression of D?

A

No, because the majority of weak D are not at risk of sensitization; need genotyping to distinguish from partial D. Partial D are at risk of sensitization.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Rh haplotype frequencies in Caucasian, AA and AS?

A

CC: R1 (42%) > r (37%) > R2 > R0 (1r20)
AA: R0 (44%) > r (26%) > R1 > R2 (0r12)
AS: R1 (70%) > R2 (21%) > r = R0
Based on this, you can calculate that ~15% of CC and ~5% of AA are RhD negative.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is McLeod Syndrome?

A

Weak expression of Kell system antigens and absence of Kx antigen; >30 different mutations in an X-linked gene, XK; late onset myopathy, neurodegeneration, and CNS symptoms in the 4th decade; sequencing of XK has prognostic value.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Prevalence of weak D RBCs not detected by serologic reagents is approximately ___

A

0.1%, this has been associated with alloimmunlization and can be improved by RHD genotyping.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

ABO: frequencies in CC, AA and AS

A

O, A, B, AB (CC has more As, AA and AS have more Bs)
CC: 45, 40, 11, 4
AA: 49, 27, 20, 4
AS: 43, 27, 25, 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of H gene (FUT1)?

A

Add terminal fucose to type 2 precursor&raquo_space; H antigen on RBCs; loss of function of H and Se gene&raquo_space; Bombay phenotype.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of Se gene (FUT2)?

A

Add terminal fucose to type 1 precursor&raquo_space; H antigen in secretion; loss of function of Se gene&raquo_space; cannot make Le(b)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the terminal CH groups of A, B and O antigens?

A

A: GalNAc (N-acetylgalactosamine)
B: Gal (galactose)
O (H): Fuc (fucose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

FUT3 (LE) is different from FUT1 and FUT2 in what aspect?

A

FUT3 transfer a fucose to the subterminal N-acetylglucosamine (GlcNAc), rather than a fucose to the terminal galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does FUT1 and FUT2 genes interact to determine Bombay/Para-Bombay phenotype?

A

hh/sese: Bombay (strong anti-H)

hh/Sese or hh/SeSe or H(minimal)h/sese: Para-Bombay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is non-secretor phenotype?

A

20% of individuals have a defective FUT2 gene: sese. They have H antigen on RBCs but not in secretions, and they cannot make Le(b).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the phenotype corresponding to Sese/lele?

A

Le(a)-Le(b)-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the phenotype corresponding to sese/Lele?

A

Le(a)+Le(b)-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the phenotype corresponding to Sese/Lele?

A

Le(a)+Le(b)+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the carrier of ABO in secretions?

A

Type 1 glycoproteins. They are produced in epithelial cells and reside on mucins in secretions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Rank the amount of H antigen by ABO blood groups:

A

O > A2 > B > A2B > A1 > A1B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What percentage of group A individuals are A1?

A

80%; ~20% are A2; A3, Ael and Ax are much less frequent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the prevalence of anti-A1 in A2 and A2B individuals?

A

1-8% of A2 individuals and ~30% of A2B individuals have anti-A1 due to structural difference between A1 and A2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which lectin, at a suitable dilution, can agglutinate A1 but not A2 or weaker subgroup RBCs?

A

Dolichos biflorus

Depends more on the quantitative than the qualitative difference between A1 and A2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the molecular mechanism of A2?

A
  • Absence of Type 4A glycolipids in A2, which are dominant in the A1
  • Loss of stop codon&raquo_space; extra 21 residues at C-terminus; Pro156Leu
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Lack of RhAG causes what phenotype?

A

Rh null or marked reduction of Rh expression;

RhAG is important for brining the RhD and RhCE proteins to the membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of RhAG?

A

Ammonia/ammonium transport and cation balance in RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Is RhAG immunogenic and clinically significant?

A

Antigen of high prevalence: RHAG1 and RHAG3
Antigen of low prevalence: RHAG2 and RHAG4
RHAG4 has been associated with strong DAT in a baby thus requiring exchange transfusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Molecular mechanism of weak-D?

A
  • Over 75 different mutations in RHD
  • RHC in trans to RHD (Dce/Ce)
  • Del (?)
26
Q

What is the most common form of partial D in CC and AA?

A

CC: DVI; routine testing with IgM monoclonal anti-D reagent does not detect it.
AA: DIIIa; these give strong reactions in serologic tests using anti-D.

27
Q

What is the mechanism of partial D?

A

Many arise as a result of nucleotide exchange between RHCE and RHD; less often they result from single-point mutations in RHD

28
Q

What is the difference between big C and little c?

A

6 nucleotide substitutions&raquo_space; 4 aa changes

29
Q

What is the difference between big E and little e?

A

1 nucleotide substitution&raquo_space; Pro226Ala

30
Q

What is G antigen?

A

The 4 aa shared by RhD and RhC, encoded by exon 2; anti-G mimicks anti-D plus anti-C; pregnant women with anti-G (but without anti-D) are still candidates for RhIG to prevent anti-D.

31
Q

What is V antigen?

A

Low-freq antigen present in 30% AA; results from Leu245Val in the Rhce protein

32
Q

What are partial e antigens?

A

Individuals of African descent often have altered RHCE*ce genes encoding partial antigens. The RBCs phenotype as e positive, but they can make alloantibodies with e-like specificities (e.g. anti-hr(s), -hr(B), -RH18 and -RH34)

33
Q

Most individuals, especially of European descent, who are D-negative have what kind of change to the RHD gene?

A

Deletion.
D-negative phenotype can also result from various mutations in RHD (premature stop codons, insertions, deletions, or RHD/RHCE hybrid alleles)

34
Q

Where and when are RhD, RhCE and RhAG proteins expressed?

A

Where: erythroid and myeloid cells
When: during late erythropoiesis with RhAG expressed earlier

35
Q

What is the rate of alloimmunization to RhD in D-negative individuals?

A

Hospital setting: 20%

Healthy male volunteers: 80% (in response to as little as 0.5 mL of D-positive RBCs)

36
Q

Antibodies specific to which Rh antigens can cause severe HDFN?

A

Anti-D and anti-c.

Anti-C, -E and -e usually cause no or mild HDFN.

37
Q

Autoantibodies that seem to target Rh antigens may be an artifact of what?

A

Using Rh-null RBCs in the testing. These cells have dcreased expression of other proteins in the Rh complex (CD47, LW, GPB-SsU antigens, and RhAG). Extended antigen-match should be the way to go for transfusion support.

38
Q

What antibody can people with Jk(a-b-) make?

A

Anti-Jk3; Jk(a-b-) is rare among both white and black people.

39
Q

What is the null phenotype lacking M and N antigens and high prevalence antigen(s)?

A

En(a-)

40
Q

What are the features of the extracellular segment of glycophorin B?

A

N (Leu-Ser-Thr-Thr-Glu) > S/s > U

41
Q

What is the phenotype of M(k)M(k) RBCs?

A

Lack both MN and Ss antigens

42
Q

What is the physiological function of GPA?

A

receptor for bacteria, viruses and P. falciparum; chaperone for Band 3 transport to RBC membrane; major contributor to the negatively charged RBC glycocalyx; may also regulate complement

43
Q

What is the physiological function of GPB?

A

Member of the Rh-complex; null phenotypes are not associated with known health defects

44
Q

What does FYX allele encode?

A

Weak expression of Fy(b); found in whites; due to a single point mutation in the 1st intracellular loop

45
Q

What is the greatest variation between whites and blacks regarding Duffy antigen frequency?

A

49% of whites are Fy(a+b+), 68% of blacks are Fy(a-b-)

46
Q

What is the major mechanism for the Fy(a-b-) phenotype in blacks?

A

A mutation in the promoter region of FYB that disrupts a binding site for GATA-1&raquo_space; loss of Duffy expression on RBCs

47
Q

What is the physiological function of Duffy antigen?

A

DARC (a promiscuous chemokine receptor binding both C-X-C and C-C; receptor for P. vivax and P. knowlesi

48
Q

Which gene is responsible for I antigens?

A

IGnT (GCNT2) encode the acetyl-glucosamine transferase that increase branching of straight chain (i) to form I antigen

49
Q

What is the gene and its encoded enzyme underlying P(k) and P1 (originally named P)?

A

A4GALT (4-alpha-galactosyltransferase): Gal alpha(1-4)-Gal beta(1-4)-…

50
Q

What is P antigen? What is the genetic basis?

A

Defined by terminal GalNAc residuals on top of P(k); now belongs to the GLOB system; enzyme encoded by beta3GALNT1

51
Q

What is p phenotype or Tj(a-)? Why is it clinically important?

A

Null of the system (inactivating mutations in A4GALT); can form alloanti-PP1P(K) which is hemolytic and of clinical significance; associated with a high rate of spontaneous abortion

52
Q

What is the difference between P1 and P2 phenotype and the molecular basis?

A

Changes in exon2a of A4GALT results in transcriptional down regulation in P2.

53
Q

The rare p phenotype is resistant to which viral infection?

A

Parvovirus B19; P antigen is the receptor for B19 parvovirus

54
Q

P1 is the receptor for which microorganisms?

A

E. coli and Streptococcus suis

55
Q

What autoantibody causes paroxysmal cold hemoglobinuria (PCH)?

A

Autoanti-P (biphasic IgG antibody, Donath-Landsteiner antibody)

56
Q

What is the ISBT definition of a blood group system?

A

Consists of one or more antigens controlled at a single gene locus, or by two or more very closely linked homologous genes with little or no observable recombination between them.

57
Q

What is the ISBT definition of a collection?

A

Consists of serologically, biochemically or genetically related antigens (controlled by unknown genes)

58
Q

Inactivating mutations in which gene define the Jr(a-) or null phenotype?

A

ABCG2 (ATP-binding cassette, subfamily G, member 2): involved in transport of urate and possibly other compounds

59
Q

Which glycoprotein is defective in Glanzmann’s thrombasthaenia?

A

GPIIb/IIIa: receptor for fibrinogen (also fibronectin, vitronectin and vWF)

60
Q

Which glycoprotein is defective in Bernard-Soulier syndrome?

A

GPIb/V/IX: receptor for vWF; show defect in platelet aggregation assay with ristocetin.

61
Q

What are the top three antigens involved in NAIT?

A

HPA-1a (68%) > HPA-5b (15%) > HPA-1b (6%) (BCW data)

62
Q

Immunization to HPA-1a is highly correlated with which HLA allele?

A

HLA-DRB301:01 and HLA-DRB401:01 (need to verify this; read the original reports)

Hillyer (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions