Prevalence of the single-nucleotide polymorphism rs11554137 (IDH1) in brain tumors of a cohort of Italian patients.

IDH mutational status is required for proper diagnosis according to the WHO criteria revised in 2016. The single nucleotide polymorphism (SNP) rs11554137 (IDH1) at codon 105 of IDH1 has been reported in patients with several tumor types, including those with glioma. The aim of this study is to investigate the prevalence of IDH1 in a cohort of brain tumors, and its association with clinicopathologic features and IDH1 and IDH2 missense mutations. Exon 4 of IDH1 and IDH2 was analyzed in a series of brain tumors classified according to current WHO criteria. DNA from control individuals was analyzed to infer the prevalence of IDH1 in the reference population. Analysis was performed using next generation sequencing. IDH1 was three times more frequent in patients with tumors (44/293 cases, 15.0%) vs. population controls (6/109, 5.5%) (p = 0.0102). IDH1 was more frequent in grade III tumors (26.1%) compared to grade II (10.9%, p = 0.038) and grade IV tumors (13.7%, p = 0.041). IDH1 was more frequent in grade II and III tumors without an IDH tumor missense mutation (43.8%) than in those with (11.5%, p = 0.005). The IDH1 SNP likely represents an important genetic marker, worthy of additional investigation to better understand the clinical and biological features of IDH-WT infiltrating gliomas.