NOD2 and Crohn disease: Moreover, these authors highlighted a subset of IBD cases with the recessive inheritance of NOD2 alleles and a substantially higher risk of early CD onset; their analyses unequivocally showed more significant effects for NOD2 homozygotes and compound heterozygotes than carriers of single NOD2 genetic variants only, and indicated that the genetic contribution of NOD2 alleles, in a subset of Crohn’s disease patients, suggests a recessive disease model [23].