Nucleoside diphosphate-linked moiety X-type motif 15 R139C genotypes impact 6-thioguanine nucleotide cut-off levels to predict thiopurine-induced leukopenia in Crohn’s disease patients

Table 2 Relationship between concentrations of 6-thioguanine nucleotide and thiopurine-induced leukopenia in different nucleoside diphosphate-linked moiety X-type motif 15 R139C genotype groups among 411 patients according to receiver operating characteristic curves

NUDT15 genotype (No. of patients)	6TGNs (pmol/8 × 108 RBC)	P value	AUC	95%CI	Sensitivity (%)	Specificity (%)
CT + CC	≥ 474.7	0.071	0.57	(0.49-0.65)	34.7	82.6
CC (342)	< 474.7	9.4 × 10-5		(0.61-0.79)	60.0	73.3
	≥ 411.5		0.70
	< 411.5
CT (65)	≥ 319.2	0.039	0.65	(0.51-0.79)	42.4	96.9
	< 319.2

In subgroups, the area under the curve was increased from 0.57 to 0.65 and 0.70. Moreover, in the CT group, the specificity was as high as 96.9%, with a sensitivity of 42.4%, and in the CC group, the specificity was 73.3%, with a high sensitivity of 60.0%, compared with the values in the total samples. AUC: Area under the curve; NUDT15: Nucleoside diphosphate-linked moiety X-type motif 15; RBC: Red blood cells.