We expand the knowledge about TTC7A deficiency, describing a patient with the mild phenotype of TTC7A deficiency but presenting overlapping features of SD/THE and MIA-CID: intestinal atresia and inflammatory bowel disease evocative of MIA-CID, but also dental abnormalities, huge forehead, liver abnormalities, autoimmune thyroiditis and hypogammaglobulinemia, evocative of SD/THE.
Gene expression analysis reveals that barrier-function-related inflammatory bowel disease (IBD) susceptibility genes (e-cadherin, hnf4a, ttc7a) are suppressed, while inflammatory response genes are stimulated in the mutants.
While specific mutations in interleukin 10 (IL-10), the IL-10 receptor (IL-10R), and mutations in NCF2, XIAP, LRBA, and TTC7 have been identified in VEO-IBD, polymorphisms in these genes are also associated with increased risk of developing IBD in adolescence or adulthood.
Mutations of the tetratricopeptide repeat domain 7A gene have been identified in patients with MIA and other related disorders, including MIA associated with combined immunodeficiency and very early onset inflammatory bowel disease with apoptotic enterocolitis.
Our study highlights variability in the phenotypic expression resulting from TTC7A deficiency and outlines that impairment of both epithelial cells and lymphocytes cooperatively causes IBD.