AIM: To examine genetic variation of nucleotide oligomerization domain 1 (NOD1 ) and NOD2 ,their respective influences on Crohn’s disease phenotype and gene-gene interactions. METHODS: (ND1+326561 ) NOD1 polymorphism and SNP8,SNP12 and SNP13 of NOD2 were analyzed in 97 patients and 50 controls. NOD2 variants were determined by reaction restriction fragment length polymorphism analysis. NOD1 genotyping and NOD2 variant confirmation were performed by specific amplification and sequencing. RESULTS: The distribution of NOD1 polymorphism in patients was different from controls (P = 0.045) and not altered by existence of NOD2 mutations. In this cohort,30.92% patients and 6% controls carried at least one NOD2 variant (P < 0.001) with R702W being the most frequent variant. Presence of at least one NOD2 mutation was inversely associated with colon involvement (9.09% with colon vs 36.4% with ileal or ileocolonic involvement,P = 0.04) and indicative of risk of penetrating disease (52.63% with penetrating vs 25.64% with non-penetrating or stricturing behavior,P = 0.02). L1007finsC and double NOD2 mutation conferred the highest risk for severity of disease (26.3% with penetrating disease vs 3.8% with non-penetrating or stricturing behavior presented L1007finsC,P = 0.01 and 21.0% with penetrating disease vs 2.5% with non-penentrating or stricturing behavior carried double NOD2 mutation,P = 0.007). Exclusion of patients with NOD2 mutations from phenotype/NOD1 -genotype analysis revealed higher prevalence of 11 genotype in groups of younger age at onset and colonic location. CONCLUSION: This study suggests population differences in the inheritance of risk NOD1 polymorphism and NOD2 mutations. Although no interaction between NOD1 -NOD2 was noticed,a relationship between disease location and Nod-like receptor molecules was established. METHODS: (ND1 + 326561) NOD1 polymorphism and SNP8, SNP12 and SNP13 of NOD2 were analyzed in AIM: To examine genetic variation of nucleotide oligomerization domain 1 (NOD1) and NOD2, their respective influences on Crohn’s disease phenotype and gene- NOD2 genotyping and NOD2 variant confirmation were performed by specific amplification and sequencing. RESULTS: The distribution of NOD1 polymorphism in patients was different from controls (P = 0.045) and not altered by existence of NOD2 mutations. In this cohort, 30.92% patients and 6% controls carried at least one NOD2 variant (P <0.001) with R702W being the most frequent variant. Presence of at least one NOD2 mutation was inversely associated with colon involvement (9.09% with colon vs 36.4% with ileal or ileocolonic involvement, P = 0.04) and indicative of risk of penetrating disease (52.63% with pen etrating vs 25.64% with non-penetrating or stricturing behavior, P = 0.02). L1007finsC and double NOD2 mutation conferred the highest risk for severity of disease (26.3% with penetrating disease vs 3.8% with non-penetrating or stricturing behavior presented L1007finsC, P = 0.01 and 21.0% with penetrating disease vs 2.5% with non-penentrating or stricturing behavior carried double NOD2 mutation, P = 0.007). Exclusion of patients with NOD2 mutations from phenotype / NOD1 -genotype analysis revealed high prevalence of 11 genotype in groups of younger age at onset and colonic location. CONCLUSION: This study suggests population differences in the inheritance of risk NOD1 polymorphism and NOD2 mutations. Although no interaction between NOD1 -NOD2 was noticed, a relationship between disease location and Nod-like receptor molecules was established.