ABO methylation analysis in patient specimens with ABO allelic loss of expression.

In the ID column a F prefix denotes patients analyzed by flow cytometry while a S prefix denotes loss of ABH antigen patients as detected by serology. ‘GENO’ refers to ABO genotype, ‘METH’ to ABO promoter CpG island methylation assessed either by MS-SSCA, COBRA and/or melt curve analysis (MCA). ‘U’ unmethylated at the ABO promoter and ‘M’ is methylated at the ABO promoter. For patient F60 two samples were available for analysis; the 1993 ('93) sample was positive for ABO expression whereas the 1996 ('96) sample was negative for ABO expression.