Molecular identification of rare FY*Null and FY*X alleles in Caucasian thalassemic family from Sardinia.

Molecular genetic studies on Duffy blood group antigens have identified mutations underlying rare FYNull and FYX alleles. FYNull has a high frequency in Blacks, especially from sub-Saharan Africa, while its frequency is not defined in Caucasians. FYX allele, associated with Fy(a-b+w) phenotype, has a frequency of 2-3.5% in Caucasian people while it is absent in Blacks. During the project of extensive blood group genotyping in patients affected by hemoglobinopathies, we identified FYX/FYNull and FYA/FYNull genotypes in a Caucasian thalassemic family from Sardinia. We speculate on the frequency of FYX and FYNull alleles in Caucasian and Black people; further, we focused on the association of FY*X allele with weak Fyb antigen expression on red blood cells and its identification performing high sensitivity serological typing methods or genotyping.