Abstract
Abstract 4992
Multiple myeloma (MM) is characterized by frequent and complex genomic abnormalities. However, most genetic abnormalities are already present in the precursor state of MM, the monoclonal gammopathy of undetermined significance (MGUS). Therefore, it is likely that secondary genetic events might contribute to the development from MGUS to symptomatic MM. Mutations in isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) genes have recently been described as relatively frequent molecular lesions in gliomas and in acute myeloid leukemia (AML). However no larger study has so far examined the frequency of IDH1 and IDH2 gene mutations in patients (pts) with MM.
In 188 pts with MM genomic DNA from CD138 sorted plasma cells was used for analyses. Exon 4 of both IDH1 and IDH2 were amplified by PCR and the amplicons were analyzed using a combination of denaturing high-performance liquid chromatography and DNA sequencing. All patients were also characterized by a comprehensive set of FISH probes for the presence of recurring cytogenetic abnormalities.
185 out of 188 samples were evaluable for analyses. One missense mutation in the IDH2 gene (c.G419A) was identified in the cohort of 185 MM pts (0.5%). This mutation was described as the most frequent IDH2 mutation in AML and is predicted to cause an amino acid change from arginine to glutamin at position 140 (p.R140Q). On cytogenetic analysis this patient harbored a translocation t(11;14) resulting in aberrant expression of CCND1. Additionally, in 15 pts (8%) the recently described single nucleotide polymorphism (SNP) in the IDH1 gene (rs11554137) was detected that has been reported as an adverse prognostic factor in cytogenetically normal AML.
Mutations in the IDH1/2 genes are a rare event in MM (0.5%). Further studies are warranted to address the issue if IDH1/2 mutations are restricted to distinct genetic subgroups as for example the group of MM pts with translocation t(11;14).
No relevant conflicts of interest to declare.
Author notes
Asterisk with author names denotes non-ASH members.
