A new missense variant in exon 7 of the ABO gene, c.662G>A, in a family with B w phenotype.
1 BACKGROUNDWeak 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 ha
