LAUSR

Weak expression of ABO antigens is encountered in the clinical laboratory occasionally, and subgroups of A are more commonly observed in Europeans than subgroups of B. To date, weakly expressing B variant phenotypes have been associated with 38 different alleles according to ISBT (https://www.isbtweb.org/resource/001aboalleles.html). This number is an underrepresentation since there have been several reports of aberrant B expression due to variant alleles since the last update of the ISBT allele table. The current study was initiated by an unusual blood group typing result in a 55-year-old male patient of Czech origin and previously reported as an abstract.