BAT-25 and BAT-26, two mononucleotide microsatellites, are not sensitive markers of microsatellite instability in acute myeloid leukaemia

BAT-25 and BAT-26 are mononucleotide microsatellites with quasi-monomorphic allele length distribution in healthy controls but unstable, shortened alleles in solid organ tumours with a mutator phenotype (RER+). Both markers are highly sensitive and specific for RER+ colorectal cancer. This study evaluated three mononucleotide microsatellites, BAT-25, BAT-26 and BAT-40 (a polymorphic mononucleotide microsatellite) in RER+ acute myeloid leukaemia (AML). Sixteen [six therapy-related AML (t-AML), 10 de novo AML] known RER+ AML, 22 healthy controls and five known RER- AML samples were analysed. In healthy controls and RER- AML, BAT-25 and BAT-26 were quasi-monomorphic and BAT-40 was polymorphic. Of the RER+ AML samples, 0 of 16 had microsatellite instability (MSI) at BAT-25, 0 of 16 had MSI at BAT-26 and three of 16 had MSI at BAT-40. We conclude that BAT-25, BAT-26 and BAT-40 microsatellites are insensitive to RER+ AML. Further studies are required to determine a consensus panel of sensitive microsatellites for use in AML.