MNSs blood group glycophorin variants in Taiwan: a genotype-serotype correlation study of 'Mi(a)' and St(a) with report of two new alleles for St(a).

BACKGROUND

Glycophorin variants of the MNSs blood group are important in Taiwan. For more than 20 years, screening for the most frequent irregular antibody, anti-''Mi(a)', has been conducted by using 'Mi(a)'(+) RBCs, with a significant success. However, the sensitivity and the specificity of this screening strategy have never been validated, and the true incidences of different glycophorin variants in Taiwan have been in controversy. Also, the significance of another less frequent and usually separately reported variant, St(a), has never been evaluated.

METHODOLOGY/PRINCIPAL FINDINGS: We ran a population-based screening (from unselected patients in our hospital) for MNSs blood group glycophorin variants by PCR-sequencing method. GP.Mur (Mil.III) was confirmed by sequence from 57 out of 1027 samples (5.6%), and there was no other Miltenberger subtype glycophorin variant found. Glycophorin variant St(a) was found from 35 out of 1027 samples (3.4%). In contrast to anti-'Mi(a)', which is the most frequently identified irregular antibody in Taiwan, the prevalence of anti-St(a) was only 0.13% as determined by serologic method. In addition, two new alleles for St(a) were found and reported.

CONCLUSION/SIGNIFICANCE: We confirm the long-standing assumption that GP.Mur is the only prevalent Miltenberger subtype in Taiwan. The current anti-'Mi(a)' screening method used in Taiwan, although neither sensitive nor specific, is still a suitable practice. Although St(a) antigen has a high prevalence in Taiwan, routine screening for anti-St(a) is not warranted based on current evidence.