<prompt> Crohn;s disease is associated withNOD2CARD15 geneP53 supressor genePhiladelpha chromosomesBRACI gene  <response>: .10 of first degree relatives; 50 of monozygotic twins develop Crohns disease. Genes NOD2 CARD15 in chromosome 16q12 has got strong association with Crohns disease. CARD15 is expressed in Paneth cells of the ileum. Smoking is related to Crohns disease as aetiology, as for relapse and for exacerbations. There is increased mucus membrane permeability - antigen induced cell mediated inflammatory response - release of cytokines like TNF, interleukin 2 -m defect in suppressor T cell - granuloma and other pathology. ref:SRB;s manual of surgery ,ed 3,pg no 801 