What enzyme do YT blood group antigens reside on?
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YT blood group antigens reside on acetylcholinesterase (AChE).
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What enzyme do YT blood group antigens reside on?
YT blood group antigens reside on acetylcholinesterase (AChE).
What is the role of the disulfide bonds in ACKR1?
They link the amino-terminal domain to the third extracellular loop and also form a bond between the first and second extracellular loops.
Where is AE1 expressed in the kidney and what is its function there?
AE1 is expressed along the basolateral membrane of type A intercalated cells of renal collecting ducts, functioning in acid secretion and bicarbonate reabsorption.
What causes the Fy x phenotype characterized by weak Fy b expression?
An R89C substitution in the first cytoplasmic loop, leading to protein instability.
What is the molecular basis of the Jk a/Jk b polymorphism?
A single-bp transition (G823A) resulting in an Asp280 (Jk a) or Asn280 (Jk b).
What genetic mutation is associated with Southeast Asia ovalocytosis (SAO)?
SAO is due to a 27 bp deletion (SLC4A1 Δ27) in the amino-cytoplasmic domain of AE1.
What is the structure of the ACKR1 glycoprotein?
It is a 336-338 amino acid integral membrane glycoprotein with a 62 amino acid extracellular amino-terminus, seven transmembrane domains, and an intracellular carboxy-terminus rich in serine and threonine residues.
What is the function of ACKR1 on red cells?
It functions as a 'chemokine sink' to control blood chemokine concentrations.
What is the biological role of Acetylcholinesterase (AChE) in the body?
It is required for the rapid degradation of acetylcholine on postsynaptic membranes of nerves and muscles.
Which blood group system contains the antithetical antigens Sc1 and Sc2?
The Scianna (Sc) blood group system.
What does the third extracellular loop of the Kidd glycoprotein likely influence?
Urea transport.
What is the current name of the Duffy glycoprotein formerly known as DARC?
ACKR1 (atypical chemokine receptor 1).
What is the clinical significance of the anti-Fy6 antigen?
It is the epitope for an anti-Duffy monoclonal antibody that blocks P. vivax binding.
What is the clinical significance of antibodies against Duffy antigens?
They are associated with hemolytic disease of the fetus and newborn (HDFN) and both immediate and delayed hemolytic transfusion reactions.
What is a notable feature of the urea transporter (UT-B) related to the Kidd blood group system?
It is a 43- to 45-kD multipass glycoprotein with 10 transmembrane domains and expresses ABO antigens.
Where do the Jk a/Jk b antigens reside?
On the fourth extracellular loop at amino acid 280.
What is the primary function of AE1 in red blood cells?
AE1 mediates the exchange of HCO3− ions for Cl− ions in plasma, known as the Cl− shift or Hamburger shift.
What is the incidence of the Yt a antigen among white donors?
The Yt a antigen is expressed by 99.8% of white donors.
What unique requirement does anti-Fy5 need for reactivity?
The presence of Rh antigens.
What is the molecular basis for the Xg(a–) phenotype in both men and women?
A mutation (rs31103G>C) located 3.7 kb upstream of the XG transcription start site that disrupts binding of the erythroid transcription factor GATA1.
What protein do Scianna antigens reside on?
Erythrocyte membrane-associated protein (ERMAP).
What is Wr b in the Diego blood group system associated with?
Wr b is topically associated with GYPA in the RBC membrane.
When was the YT blood group system discovered and what are its primary antigens?
The YT blood group system was discovered in 1956 and includes five antigens, with Yt a and Yt b being the primary autosomal-codominant antigens.
Where is the Duffy gene (ACKR1) located?
On chromosome 1q22-23.
How is the Jk null phenotype inherited?
It is autosomal recessive, requiring homozygosity for amorph JK null alleles.
How many Jk null alleles are recognized by ISBT?
24 Jk null alleles.
What does the AE1 glycoprotein bind to in its amino-terminal cytoplasmic domain?
It binds several key cytoskeletal proteins such as Band 4.1, Band 4.2, and ankyrin, and glycolytic enzymes.
Where else are Duffy antigens expressed besides RBCs?
Duffy antigens are also expressed on cerebellar Purkinje cells, postcapillary venule endothelial cells, and other tissues such as renal glomeruli and pulmonary capillaries.
What role does AE1 play in red blood cell cytoskeleton?
AE1 impacts membrane stability and red cell circulation.
In which demographic is Anti-Fy b predominantly observed?
Primarily in nonblacks.
What is the association between the Fy null phenotype and neutropenia?
In humans, the Fy null phenotype is associated with benign ethnic neutropenia.
How does the Fy null phenotype affect susceptibility to P. vivax?
Fy null individuals are resistant to most P. vivax strains, providing a selective advantage in malaria-endemic areas.
What is the genetic basis of the Kidd glycoprotein?
It is encoded by a 30-kb gene (JK, SLC14A1, UT-B) on chromosome 18q12-21.
What biological role do Lewis blood group antigens play in disease?
Le(a–b–) phenotype is linked to a higher risk of atherosclerotic disease and coronary death, and aberrant expression of sialyl-Lea occurs in many gastrointestinal and uro-epithelial cell cancers.
How is the Cl− shift facilitated in red blood cells?
The Cl− shift is facilitated by AE1, which allows the exchange of HCO3− ions for Cl− ions.
In which populations does the incidence of the Yt b antigen vary significantly?
The incidence of the Yt b antigen varies from 0% in Japanese to 24%-26% in the Middle East.
Which is the most common alloantibody against Duffy antigens?
Anti-Fy a.
What is the reference allele for the Diego blood group system?
Di(b+) is considered the reference allele (DI*02).
Which Duffy antigens are resistant to protease digestion?
Fy5 and Fy3 antigens.
What are the missense mutations responsible for the loss of high-incidence antigens in the YT blood group system?
Gly89Glu for YTEG (YT03), Gly57Arg for YTLI (YT04), and Arg34Gln for YTOT (YT*05).
What are the predominant Duffy alleles responsible for the common phenotypes?
FYA (FY01), FYB (FY02), FYB ES (FY02N.01), and FYX (FY02W).
Where is the ERMAP gene located, and what is its structure?
It resides on chromosome 1p34 and consists of 11 exons spanning 19 kb.
What is the role of the AE1 glycoprotein in the Diego blood group system?
AE1 functions as an anion transporter, facilitating the movement of Cl− and HCO3− anions across the cell membrane.
What are the characteristics of Lewis antibodies?
They are naturally occurring IgM antibodies, detected as room temperature agglutinins, and are seldom clinically significant.
How do anti-Fy3 antibodies react with Duffy-positive RBCs?
Anti-Fy3 reacts like anti-Fy a+b, reacting with all Duffy-positive RBCs.
Why is the incidence of the Xgᵃ-positive phenotype higher among women?
Because the Xgᵃ antigen is encoded by a gene on the X chromosome.
What is the biological role of JK/UT-B in the kidney?
It helps stabilize osmotic gradients in the renal medulla during the concentration of urine.
What is the predominant Duffy phenotype in blacks?
The Duffy null or Fy(a–b–) phenotype is predominant in blacks.
What phenotype is considered embryonic lethal due to the importance of AE1?
The Diego null phenotype is considered embryonic lethal.
What is the molecular basis for the Yt a and Yt b antigens?
The Yt a and Yt b antigens represent a single-amino acid polymorphism at residue 322, where His322 is Yt a and Asn322 is Yt b.
What are the major Duffy antigens and where are they located?
The Fy a, Fy b, and Fy6 antigens are located on the amino-terminal domain of ACKR1.
What are the two known ACKR1 mRNA transcripts and the proteins they produce?
The transcripts produce a 336 amino acid protein (isoform B, predominant) and a 338 amino acid protein (isoform A, minor).
Which isotype are anti-Ytᵃ and anti-Ytᵇ antibodies usually?
IgG isotype.
What is the relationship between the XG protein and MIC2 (CD99) in the RBC membrane?
They are associated possibly as a heterodimer, with MIC2 inhibiting anti-Xgᵃ antibodies and coimmunoprecipitating with anti-Xgᵃ. In women, Xg(a–) is associated with low CD99 expression, while in Xg(a–) men, CD99 is elevated.
What is the mutation associated with Lewis-active substance in saliva and its effect?
A single missense mutation in the transmembrane domain (T59>G) leads to decreased Golgi retention and reduced activity with glycolipid substrates, causing discrepant Lewis expression.
What diseases is AE1 recently identified as a receptor for?
AE1 is a receptor for Bartonella, which causes Oroya fever, trench fever, bacillary angiomatosis, and cat scratch disease.
Which amino acid residues are critical for P. vivax binding on ACKR1?
Amino acids 19 to 26, which form the Fy6 epitope.
What are the causes of the Fy null or Fy (a–b–) serologic phenotype in whites and blacks?
In whites, the FY gene is disrupted (FY*amorph), leading to the absence of DARC on all tissues. In blacks, it is due to a mutation in the FY gene promoter (–67T>C) which selectively disrupts FY transcription in RBCs.
What are the primary antigens in the Kidd blood group system?
The primary antigens are Jk a (JK01) and Jk b (JK02).
How many exons does the JK gene have and which ones encode the mature protein?
The JK gene is organized over 11 exons, with exons 4 to 11 encoding the mature protein.
How many Diego antigens exist and what is the most common among native South American Indian populations?
The Diego blood group system consists of 22 antigens, with Di a being the most common among native South American Indian populations.
What role do Lewis antigens play in infectious diseases?
Secretor status impacts susceptibility to infectious diseases; for example, Helicobacter pylori binds to H, Leb, and Ley antigens, and nonsecretors have higher resistance to certain infections.
What differentiates the codominant alleles FYA and FYB?
They differ by a single amino acid (Gly42Asp).
How is the Fy null phenotype linked to renal disease and transplant outcomes?
It is linked to renal disease, reduced graft survival following renal transplantation, and insulin resistance.
What is the clinical relevance of anti-Xgᵃ antibodies?
They are not associated with hemolytic transfusion reactions or HDFN. Most examples are of IgG isotype, and more than 85% are observed in men.
What are the specific features of the ERMAP protein in the Scianna blood group system?
It is a 60- to 68-kD glycoprotein, a type 1 single-pass transmembrane protein with a single IgV domain, a large cytoplasmic domain, 11 cysteine residues, and sensitivity to sulfhydryl-reducing agents.
What is the consequence of being Le/le heterozygous for the FUT3 gene?
These individuals show a 50% decrease in FUT3 activity in saliva and tissues.
What is the clinical significance of Cartwright antibodies anti-Ytᵃ and anti-Ytᵇ?
They are usually clinically benign but can result in shortened red cell survival and delayed hemolytic transfusion reactions. They are not associated with HDFN.
How many antigens does the Xg blood group system contain and what are the known phenotypes?
It contains a single antigen, Xgᵃ, with two known phenotypes: Xgᵃ-positive and Xgᵃ-negative.
What are anti-Jk antibodies and why are they clinically significant?
They are a common cause of hemolytic transfusion reactions, accounting for nearly one-quarter of all delayed hemolytic transfusion reactions and 75% of those with true hemolytic sequelae.
What is the Duffy blood group system and what are its main antigens?
The Duffy blood group system includes five antigens: Fya, Fyb, Fy3, Fy5, and Fy6. Fya and Fyb are autosomal-codominant, while Fy3, Fy5, and Fy6 are high-incidence antigens.
What selective advantage might the enhanced migration of neutrophils provide?
It could represent a selective advantage against bacterial infection.
What is a significant characteristic of Jk null RBCs?
Jk null RBCs are resistant to lysis by 2M urea.
What type of antibodies are Kidd antibodies usually?
They are usually of IgG1 or IgG3 isotype and are capable of activating complement.
What is the function of the AE1 glycoprotein in gas transport and acid-base equilibrium?
AE1 facilitates the removal of CO2 by hydrating it via carbonic anhydrase.
What gene resides on chromosome 19q13.3 and what other genes are part of its cluster?
The FUT2 (Se) gene resides on chromosome 19q13.3 as part of a 100-kb gene cluster that includes the H gene (FUT1) and Sec1, an inactive FUT2-like pseudogene.
Which phenotypes are associated with the anti-Lea and anti-Leb antibodies?
Anti-Lea is observed in Le(a–b–) individuals, while anti-Leb can be observed in Le(a+b–) or Le(a–b–) individuals.
