ALPI and complement component 3 deficiency: Among all the altered expression of gene, the ALPI gene was selected as the novel functional gene for constipation because the expression level of this gene was downregulated in Lop-induced constipation and C3 deficiency-induced constipation as well as the fact that the deficiency of the protein encoded by ALPI had been investigated as the cause of inflammatory bowel disease (IBD) [10,13].