Table 1.

IDH Mutation Testing (Total n = 135)

Test Modalities, n (%)	IDH Mutation
	IDH1 R132H (n = 104, 77%)	IDH2 R172K (n = 6, 4%)	Not Detected (n = 25, 19%)
IHC for mutant IDH1 R132H protein
IHC only	13	NA	6
Confirmed by allele-specific PCR	2	NA	2
Confirmed by gene sequencing	59	NA	15
Allele-specific PCR only	5*	0	0
Gene sequencing only	25*	6	2

Abbreviations: IDH, isocitrate dehydrogenase; IHC, immunohistochemistry; NA; not applicable; PCR, polymerase chain reaction.

*IDH1 R132H mutation was detected by PCR (n = 1) and gene sequencing (n = 8) in patients with IHC false-negative tumors.