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Duffy Null Allele

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D J Thornton
Posts: 304
Joined: Sat Aug 01, 2015 3:58 am

Duffy Null Allele

Postby D J Thornton » Wed Aug 05, 2015 10:53 am

The presence of the Duffy Null Allele in your DNA confirms African Ancestry. The absence of it doese not disprove African Ancestry. It is a likely indicator.
This question was brought to me by a member , here is some info
The Duffy blood group - Blood Groups and Red Cell Antigens - NCBI Bookshelf

The Duffy glycoprotein is a receptor for chemicals that are secreted by blood cells during inflammation. It also happens to be a receptor for Plasmodium vivax, a parasite that invades red blood cells (RBCs) and causes malaria. RBCs that lack the Duffy antigens are relatively resistant to invasion by P. vivax. This has influenced the variation in Duffy blood types seen in populations where malaria is common.

Antibodies formed against the Duffy antigens are a cause of both transfusion reactions and hemolytic disease of the newborn.


The Duffy blood group was discovered in 1950. It was named for a patient with hemophilia who had received multiple blood transfusions and was the first known producer of anti-Fya. A year later, anti-Fyb was discovered in a woman who had had several children. The remaining Duffy antigens (FY3, FY4, FY5, and FY6) were discovered 20 years later, but from these, only FY3 appears to be clinically significant.

The frequency of the Duffy phenotypes varies in different populations. The Duffy null phenotype, Fy(a-b-), is rare among Caucasian and Asian populations, whereas it is the most common phenotype in Blacks, occurring in over two-thirds of the Black population. The racial variation in the distribution of Duffy antigens is a result of a positive selection pressure—the absence of Duffy antigens on RBCs makes the RBCs more resistant to invasion by a malarial parasite.... More

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