MIDTERM LECTURE 2: UNCOMMON BLOOD GROUPS Flashcards
How many antigens are in the Diego system?
22 antigens, including three sets of high and low antithetical pairs (Dia/Dib, Wra/Wrb, and Wu/DISK) and 16 low-prevalence antigens.
What is the ISBT designation and system number for Diego?
DI
#010
How did the Diego system get its name?
It was named after a Venezuelan family in which the first antibody was identified during an HDFN investigation.
Where is the SLC4A1 gene located?
On chromosome 17 (17q21.31).
What was the first reported Diego antibody, and when was it discovered?
Anti-Dia, reported in 1955 after causing HDFN in a Venezuelan baby.
How common is the Dia antigen?
Rare in most populations but polymorphic in Mongoloid ancestry. Its prevalence can be as high as 54% in South American Indians.
What is the prevalence of the Dib antigen?
Generally >99%, but 96% in Native Americans.
What phenotype has not been reported in the Diego system.
Di(a–b–).
Wrb requires band 3 interaction with normal glycophorin A (GPA) from which blood group for expression
MNS
phenotype of GPA-deficient RBCs
Wr(a-b-)
Which low-prevalence Diego antigen is sensitive to papain?
Bpa
T or F:
Diego antigens are expressed on RBCs of newborns
T
antibody class of Diego antibodies
usually IgG, reactive in AHG phase; sometimes IgM
Which Diego system antibodies are associated with HDFN and hemolytic transfusion reactions (HTRs)?
Anti-Dia, anti-Dib, and anti-Wra.
What condition is autoanti-Wrb associated with?
Warm autoimmune hemolytic anemia (AIHA).
Which low-prevalence Diego antigen antibody has caused severe HDFN?
anti-ELO
How many antigens make up the Yt system?
Two antigens: Yta (high-prevalence) and Ytb (low-prevalence).
How did the Yt system get its name?
Named in 1956 after the first antibody maker, whose last name was Cartwright. The system name came from the last letter “t” in Cartwright, and “why T” was shortened to Yt.
What is the ISBT designation and system number for Yt?
YT (011).
What is the prevalence of Yta and Ytb in different populations?
Yta is a high-prevalence antigen in all populations.
Ytb is found in about 8% of whites and 21%-26% of Israelis but is not found in Japanese.
What are the observed phenotypes in the Yt system?
Yt(a+b–) → Common
Yt(a+b+) → Common
Yt(a–b+) → Rare
Yt(a–b–) → Not reported
What are Yt antigens based on?
An amino acid substitution on acetylcholinesterase (AChE)
What is the function of RBC-bound acetylcholinesterase (AChE)?
Unknown, but AChE plays a key role in neurotransmission.
Where is the ACHE gene located?
On chromosome 7 (7q22.4).
How are Yt antigens affected by enzyme treatments?
Variably sensitive to ficin and papain
Sensitive to DTT
Resistant to glycine-acid EDTA
Are Yt antigens present at birth?
Yes, but they are weaker on cord RBCs than on adult RBCs.
Yt antigens are absent from RBCs of people with what disease
PNH III
What type of immunoglobulin are anti-Yta and anti-Ytb?
IgG
Which Yt antibody is more immunogenic?
Anti-Yta (anti-Ytb is rare).
T or F:
Yt antibodies have caused HDFN
F
How is the clinical significance of anti-Yta determined for transfusion?
monocyte phagocytosis assays (MMA)
When and how was Anti-Xga discovered?
In 1962, in the serum of a multiply transfused male patient.
Why was the Xga antigen named “Xg”?
X → Named after the X chromosome.
g → Stands for “Grand Rapids,” the city where the patient was treated.
What is the ISBT designation and system number for the Xg system?
XG (012).
What is the inheritance pattern of Xga?
X-linked dominant inheritance.
Why are Xg(a+) males hemizygous?
Because they have only one X chromosome (XY), while females can be homozygous or heterozygous (XX).
What genes are involved in the Xg blood group system?
XG gene (encodes Xga) – located at Xp22.32
MIC2 gene (encodes CD99) – located at Xp22.2 and Yp11
How many antigens are part of the Xg blood group system?
Two:
Xga
CD99
How many Xga antigen copies are on each RBC?
Approximately 9,000 per RBC.
How does Xga expression differ between individuals?
Xg(a+) individuals → High CD99 expression
Xg(a–) females → Low CD99 expression
Xg(a–) males:
68% have high CD99 expression
32% have low CD99 expression
How does Xga antigen expression change with age?
Cord RBCs → Weak Xga expression
Adult females → Some have weak Xga expression
Adult males → Rarely have weak expression
How does the Xga antigen react to enzyme treatment?
Sensitive to ficin and papain
Resistant to DTT treatment
What type of antibody is Anti-Xga?
Usually IgG, but some naturally occurring IgM examples exist.
Can Anti-Xga cause Hemolytic Disease of the Fetus and Newborn (HDFN)?
No, it has not been implicated in HDFN.
Has Anti-Xga been linked to Hemolytic Transfusion Reactions (HTRs)?
No, it is not clinically significant in transfusions.
What is the ISBT designation and system number for the Scianna blood group system?
SC (013).
When was the first antigen of the Scianna system discovered?
In 1962, the Sm antigen was identified as a high-prevalence antigen.
When was the second antigen discovered, and what was it originally called?
In 1963, the Bua antigen was found as a low-prevalence antigen.
How did the Scianna system become official?
When it was confirmed that Sm and Bua were antithetical, the Scianna system was officially established in 1974, renaming them as Sc1 and Sc2.
What is the gene responsible for the Scianna blood group system?
ERMAP (Erythroid Membrane-Associated Protein) gene.
Where is the ERMAP gene located?
On chromosome 1, at position 1p34.2.
What is the function of ERMAP?
It encodes an RBC adhesion protein involved in cell interactions.
what Sc antigens were added after linking it to ERMAP
Sc4, Sc5 (STAR), Sc6 (SCER), and Sc7 (SCAN)
How many antigens are currently part of the Scianna blood group system?
Seven
Identify the prevalence of Sc antigen:
Sc1
high prevalence
Identify the prevalence of Sc antigen:
Sc2
low prevalence, ~1% in Northern Europeans, higher in Mennonites
Identify the prevalence of Sc antigen:
Sc3
high prevalence
Identify the prevalence of Sc antigen:
Sc4 (Rd)
low prevalence
Identify the prevalence of Sc antigen:
Sc5 (STAR)
high prevalence
Identify the prevalence of Sc antigen:
Sc6 (SCER)
high prevalence
Identify the prevalence of Sc antigen:
Sc7 (SCAN)
high prevalence
What is the Scianna-null phenotype?
Sc:–1,–2,–3
where is Scianna-null phenotype first found
Marshall Islands in 1980
What antibody was identified in the Scianna-null individual?
Anti-Sc3
Anti-Sc3 is reactive with what RBCs
reactive with all Scianna-positive RBCs but not with Sc:–1,–2,–3 RBCs
How do Scianna antigens react to enzymes like ficin, papain, and DTT?
Resistant to ficin and papain and DTT
which Sc antigen is not resistant with DTT
Sc2
T or F:
Scianna antigens expressed on cord RBCs?
T
What type of immunoglobulin are anti-Scianna antibodies?
IgG
Have Scianna antibodies been associated with Hemolytic Transfusion Reactions (HTRs)?
no severe cases reported
Can Scianna antibodies cause Hemolytic Disease of the Fetus and Newborn (HDFN)?
Usually mild HDFN.
what Sc antibody was reported with severe HDFN
anti-Rd
Have autoantibodies against Scianna antigens been reported?
Yes, Sc1 and Sc3
What is the ISBT symbol and number for the Dombrock blood group system?
DO, 014
Who was the Dombrock system named after?
named after Mrs. Dombrock, the first person identified with anti-Do^a in 1965.
When was anti-Do^a first identified?
1965
When was anti-Do^b first identified?
1973
What are the three main phenotypes in the Dombrock system?
Do(a+b–), Do(a+b+), and Do(a–b+).
What are the high-prevalence antigens in the Dombrock system?
Gya, Hy, Joa, DOYA, DOMR, DOLG, DOLC, DODE.
What are the low-prevalence antigens in the Dombrock system?
Do^a and Do^b.
Which antigen is associated with the Dombrock null phenotype?
Gy(a–) phenotype is the Dombrock null.
What is the relationship between Gya, Hy, and Joa?
BCs that are Gy(a–) or Hy– are also Jo(a–), meaning these antigens are closely linked.
What rare Dombrock phenotypes are found only in Black individuals?
Hy– Jo(a–) and Hy+w Jo(a–).
Which Dombrock antigen is considered highly immunogenic?
Gya
T or F:
Do^a and Do^b are strong immunogens
F
(poor immunogens)
What protein carries the Dombrock antigens?
mono-ADP-ribosyltransferase 4 (ART4) protein.
which chromosome is the Dombrock (ART4) gene located?
chromosome 12 at position 12p13-p12.
How is ART4 anchored to the RBC membrane?
It is attached via a GPI (glycosylphosphatidylinositol) anchor.
Are Dombrock antigens present on cord RBCs?
Yes, they are present at birth.
Are Dombrock antigens found on PNH type III RBCs?
No
Dombrock antigens are resistant to what enzyme treatment
ficin, papain, and glycine-acid EDTA
DO antigens are sensitive to what enzyme treatment
0.2 DTT
immunoglobulin class of DO antibodies
IgG
What type of transfusion reaction is associated with anti-Do^a and anti-Do^b?
delayed HTR
What is the ISBT symbol and number for the Colton blood group system?
CO, 015
How many antigens are in the Colton blood group system?
four antigens: Co^a, Co^b, Co^3, and Co^4
Which Colton antigen is high-prevalence?
Co^a and Co^4 are high-prevalence antigens.
Which Colton antigen is low-prevalence?
Co^b is low-prevalence, found in about 10% of most populations.
Which Colton antigen is present on all RBCs except for the rare Co(a–b–) phenotype?
Co^3.
On what phenotype is Co^4 found?
Co(a–b–) phenotype.
What is the rarest Colton phenotype?
Co(a–b–)
Co(a-b-) lacks which antigens
Coa, Cob, Co3
What protein carries the Colton antigens?
Aquaporin 1 (AQP1).
What is the function of AQP1 in the body?
80% of water reabsorption in the kidneys.
which chromosome is the AQP1 gene located?
Chromosome 7, at position 7p14
Are Colton antigens present at birth?
yes
Are Colton antigens resistant or sensitive to enzyme treatment?
resistant to ficin, papain, chloroquine, DTT
What is the typical immunoglobulin class of Colton antibodies?
IgG
Which Colton antibodies have been reported to cause hemolytic transfusion reactions (HTRs)?
Anti-Co^a, Anti-Co^b, and Anti-Co^3.
Which Colton antibodies have been associated with hemolytic disease of the fetus and newborn (HDFN)?
Coa, Cob= mild HDFN
Co3= severe
How does anti-Co^3 react with RBCs?
It reacts with all Co(a+) and Co(b+) RBCs.
What is the ISBT symbol and number for the Landsteiner-Wiener (LW) blood group system?
LW, 016
What was the original name of anti-LW?
anti-Rh
