Molecular characterization of the Fy(a−b−) phenotype in a Polish family

The Fy(ab� ) phenotype, very rare in Caucasians and defined by the homozygous FY � B-33 allele, is associated with the � 33T > C mutation in the promoter region of the FY gene. The allele FY � X is correlated with weak expression of Fy b antigen due to 265C > T and 298G > A mutations in FY �