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Duffy
Question | Answer |
---|---|
Duffy glycoprotein is a receptor for these 2 things | cytokines and Plasmodium vivax |
Duffy antigen frequencies by race | Fya: 66% Caucasians, 10% Blacks, 99% Asians Fyb: 83% Caucasians, 23% Blacks, 18.5% Asians Fy3: 100% Caucasians, 32% Blacks, 99.9% Asians |
Frequency of Duffy phenotypes | The Duffy null phenotype, Fy(a-b-), is very rare in Caucasians but is found in 68% of Blacks. Fy(a+b+): 49% Caucasians, 1% Blacks, 9% Chinese Fy(a-b+): 34% Caucasians, 22% Blacks, <1% Chinese Fy(a+b-): 17% Caucasians, 9% Blacks, 91% Chinese |
Antibody type for Duffy antibodies | IgG |
Do Duffy antibodies bind complement? | No |
The Duffy null phenotype, Fy(a-b-), is the most common phenotype in this population. | most common phenotype in Blacks |
Why is there racial variation in the distribution of Duffy antigens? | Result of a positive selection pressure—absence of Duffy antigens on RBCs makes the RBCs more resistant to invasion by p.vivax |
Worldwide the Plasmodium species that is responsible for the majority of fatal cases | P. falciparum |
In Asia and the Americas, which Plasmodium species is a more common cause of malaria | P. vivax |
How does Plasmodium vivax enter an RBC? | By binding to N-terminal extracellular domain of the Duffy glycoprotein through cysteine-rich region of Duffy binding protein (DBP). Individuals with the Duffy null phenotype do not express Duffy protein on RBCs and are immune to P. vivax infection. |
The Duffy locus, FY, is located on chromosome | 1 |
genetic background that give rise to the Duffy negative phenotype Fy(a-b-) in blacks | Mutation in promoter region of FYB allele abolishes expression of Duffy glycoprotein in RBCs, protein still produced in other types of cells. (GATA mutation) |
genetic background that give rise to the Duffy negative phenotype Fy(a-b-) in which no Duffy antigens are expressed in RBCs or tissues | point mutation introduces premature stop codon into coding sequence.Unlikely that truncated Duffy protein is transported to cell surface, and likely that Duffy protein would be absent from all tissues in individuals who carry this type of mutation. |
What is the severity of Hemolytic disease of the newborn caused by anti-Duffy antibodies | Tends to be mild in nature. |