Duffy Flashcards
What chromosome is FY gene located on?
Chromosome 1
Syntenic to Rh
Far enough away that Rh and Duffy are not linked
What is the gene name for FY?
DARC
Duffy antigen receptor for cytokines
What antigens are present if FY*01 is present?
Fya, Fy3, Fy5, Fy6,
What antigens are present if FY*02 is present?
Fyb, Fy3, Fy5, Fy6
What antigens are present if FYmod is present?
Fy Mod phenotype called Fyx Reduced expression of Fyb antigens Caused by SNP Occurs in White population May require adsorption/elution
What antiges are present if FY01N or FY02N is present?
FY null = no Fy antigens
Present in Blacks
What is the frequency of Fya in Japanese?
96% are Fya+
What is the frequency of Fy(a-b-) in whites and blacks?
Very rarely occurs in whites
67% of blacks are Fy(a-b-)
- also lack Fy3 and Fy5
What is the frequency of Fya in Whites and blacks?
66% of whites are positive
13% of blacks are positive
What is frequency of Fyb in Whites and Blacks?
83% of whites are positive
23% of blacks are positive
What are the characteristics of Duffy antigens?
Well developed on cord cells
Destroyed by enzymes and ZZAP (contains enzyme)
Not affected by DTT
At what gestation can Duffy antigens be detected?
As early as 6 weeks
Where are Duffy antigens found?
Found in tissues through out the body such as the brain, lung, spleen, thyroid, thymus, and kidney
What are the characteristics of anti-Fya and anti-Fyb?
Mostly IgG1 Shows dosage Anti-Fya is common in Whites - Anti-Fya is 3x more common than anti-K Causes HDFN and TRN TRX Enhanced by LISS
What is Fy3?
High freq. present when either Fya or Fyb is present
not destroyed by enzymes (located further down protein)
Anti-Fya is usually formed first, then Fy3
What is Fy5?
Hgh freq present when Rh antigens are present and with Fya or Fyb.
Not expressed on Rh null cells regardless of Fya or Fyb expression.
Not destroyed by enzymes
Weak on Fyx and D– cells
What is Fy6?
an antigen defined by a murine monoclonal antibody
No human anti-Fy6 has been found
Absent on Fy3 negative and Fy5 negative cells
Destroyed by enzymes
What is FYmod?
Fyx is phenotype not an antigen Weak Fyb caused by SNP in Exon 2 Found in white people May required adsorpt/elution to detect monoclonal anti-Fyb may detect
What is the Fynull phenotype?
Mutation results in Fy gene that produces no DARC antigen on RBC’s
Homozygotes will have Fy(a-b-,3-5-)
Common in Blacks
What is Fy(a-b-) found in European popuation?
Very, very rare
Mutation on DARC gene affects Fy on all tissues
Can make anti-Fy3
What is GATA-1?
mutation caused by a SNP in the GATA region of the Fyb gene blocks mRNA trasnscription in RBC’s only
GATA is resposible for Fy gene in blacks Fy(a-b-)
70% of blacks are Fy(a-b-)
Unlikely to make anti-Fy3 or anti-Fy5 because Fyb is present in tissues
Characteristics of Anti-Fy3?
Can form in African Fy(a-b-) in multiply transfused patients. This antibody is negative with cord cells and directed against subtle difference in DARC on RBC’s then DARC on tissues
Anti-Fy3 formed in Caucasians will react with cord cells
Characteristics of Anti-Fy5?
All examples were seen in african Fy(a-b-) individuals
Will not react with Rh null cells and reacts weakly with D– cells
Describe the structure of Fy antigen?
Multipass protein that pass membrane 7X
Fya, Fyb, and Fy6 are located on N terminus and destroyed by enzymes
Fy3 and Fy5 are on the 3rd loop and not affected y enzymes
How can you use Duffy genotyping?
Genotype recently transfused patients
Determine if apparent Fy(b-) are actually Fyx
Determine if cells are double dose
Use for malaria and genetic studies
Determine which Fy(a-b-) carry Gata-1 mutation and can receive Fyb positive units
What is the function of DARC?
Functions as a scanvenger and removes unwanted cytokines like IL-8
It is a receptor for P. vivax and P. knowlesi
What are the markers for African ancestry?
Ro (Dce), V+, Jsa+, Le(a-b-), Fy(a-b-) Jk(a+b-), S-s-U-
