Wra-positive red blood cells
Red blood cells for the detection of Wra antibodies
Ever since Holman described the first example of anti-Wra in 1953, probably thousands of examples of this antibody have been found. Long before Wra became part of the Diego system, this resulted in it being probably the most studied of all low frequency antigens (LFAs) on serological level.
Many thousands of typing tests were carried out with anti-Wra. Different studies show that the occurrence of the Wra-antigen in the Caucasian population is on average 1 in 1365 persons. Many studies have showed an independent separation of Wra from other blood groups loci, even before Wra was recognized as an antigen in the Diego system. This means that the production of Wra is controlled by a gene on chromosome 17.
The Wra gene survives the treatment of red cells with, among others, trypsin, papain, chymotrypsin en neuraminidase. The antigen is fully developed at birth.