Anti-Fy3 aka anti-Fyc

Blood Group: Duffy

Common: Fy3 antigens are found in 100% Caucasians, 32% Blacks, 99.9% Asians. This means that 68% of blacks and 0.1% of asians would be at risk for developing anti-Fy3.

Causes HDN: Yes

Critical Titer: 1:16


HDN due to anti-Fy3 is rare and can cause moderate disease [3]. It is mentioned in the book cited below. Anti-Fy3 can only be made by individuals who are fy(a-,b-) [2]. Only 3 cases of anti-Fy3 are known in literature. 2 were in non-negro people while only 1 was black. This was surprising because the Fy(a-,b-) is most common among blacks. [3] The Red Cross briefly mentions an account of mild HDN requiring no treatment, but a positive direct coombs test was found [4].


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Reid ME and Lomas-Francis C. The Blood Group Antigen Facts Book. Second ed. 2004, New York: Elsevier Academic Press.