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 . It is mentioned in the book cited below. Anti-Fy3 can only be made by individuals who are fy(a-,b-) . 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.  The Red Cross briefly mentions an account of mild HDN requiring no treatment, but a positive direct coombs test was found .
4 - http://www.redcross.org/images/MEDIA_CustomProductCatalog/m4440094_26_2_10.pdf
Reid ME and Lomas-Francis C. The Blood Group Antigen Facts Book. Second ed. 2004, New York: Elsevier Academic Press.