Table 4.

Significance of the association of 6-MP metabolite concentrations summary measures with XO, TPMT or ITPA variant genotypes in (a) ALL patients and (b) IBD patients treated with 6-MP/AZA^*

(a) ALL patients genotype	AUC of RBC metabolite concentrations (AUC1–4 months)
	6-TGNs	6-mMPNs	6-TU	6-MP
TPMT*3 heterozygote	0.021	0.008	0.021	0.041
ITPA C94→A heterozygote	0.439	0.972	0.950	0.359
ITPA IVS2+21A→C mutant†	0.008	0.660	0.660	0.660

(b)IBD patients Genotype	Mean RBC metabolite concentrations
	6-TGNs	6-mMPNs	6-TU	6-MP
XO heterozygote	0.337	0.670	0.497	0.060
TPMT*3 heterozygote	0.866	0.038	0.187	0.670
ITPA C94→A mutant	0.670	0.154	0.822	0.497
ITPA IVS2+21A→C mutant	0.047	0.960	0.305	0.427

^*Numbers represent P-values for the corresponding association adjusted as per the Bonferroni justification for multiple testing.

^†Mutant refers to any mutant (homozygote or heterozygote). 6-MP, 6-mercaptopurine; XO, xanthine oxidase; TPMT, thiopurine S-methyl transferase; ITPA, inosine triphosphatase; ALL, acute lymphoblastic leukaemia; IBD, inflammatory bowel disease; AZA, azathioprine; 6-TGN, 6-thioguanine nucleotide; 6-mMPN, 6-methylmercaptopurine nucleotide; 6-TU, 6-thiouric acid.