6-MercaptopurineMethyltransferasesThioguanineAzathioprineMethylthioinosineInflammatory Bowel DiseasesPharmacogeneticsPurinesImmunosuppressive AgentsThionucleosidesAminosalicylic AcidsAntimetabolites, AntineoplasticAntimetabolitesGuanine NucleotidesLeukopeniaThionucleotidesPurine NucleotidesProdrugsPyrophosphatasesPolymorphism, GeneticPurine NucleosidesSulfapyridineGenotypePrecursor Cell Lymphoblastic Leukemia-LymphomaCrohn DiseaseMesalamineGallic AcidGastrointestinal AgentsErythrocytesHomozygoteColitis, UlcerativeHypoxanthineAllopurinolPhenotypeHeterozygotePolymorphism, Restriction Fragment LengthAlleles5'-NucleotidaseGene FrequencyChromatography, High Pressure LiquidDrug Interactions