Editing Ulcerative colitis (section)

===Genetic factors===
A genetic component to the cause of UC can be hypothesized based on aggregation of UC in families, variation of prevalence between different ethnicities, [[genetic marker]]s and [[Genetic linkage|linkages]].<ref name=Orholm>{{cite journal | vauthors = Orholm M, Binder V, Sørensen TI, Rasmussen LP, Kyvik KO | title = Concordance of inflammatory bowel disease among Danish twins. Results of a nationwide study | journal = Scandinavian Journal of Gastroenterology | volume = 35 | issue = 10 | pages = 1075–1081 | date = October 2000 | pmid = 11099061 | doi = 10.1080/003655200451207 | s2cid = 218907577 }}</ref> In addition, the identical [[twin studies|twin]] [[Concordance (genetics)|concordance]] rate is 10%, whereas the [[dizygotic twin]] concordance rate is only 3%.<ref name=Orholm /><ref>{{cite journal | vauthors = Tysk C, Lindberg E, Järnerot G, Flodérus-Myrhed B | title = Ulcerative colitis and Crohn's disease in an unselected population of monozygotic and dizygotic twins. A study of heritability and the influence of smoking | journal = Gut | volume = 29 | issue = 7 | pages = 990–996 | date = July 1988 | pmid = 3396969 | pmc = 1433769 | doi = 10.1136/gut.29.7.990 }}</ref> Between 8 and 14% of people with ulcerative colitis have a family history of inflammatory bowel disease.<ref name=Ungaro /> In addition, people with a first degree relative with UC have a four-fold increase in their risk of developing the disease.<ref name=Ungaro />

Twelve regions of the [[genome]] may be linked to UC, including, in the order of their discovery, chromosomes 16, 12, 6, 14, 5, 19, 1, and 3,<ref name=Baumgart/> but none of these [[Locus (genetics)|loci]] has been consistently shown to be at fault, suggesting that the disorder is influenced by multiple genes. For example, chromosome band 1p36 is one such region thought to be linked to inflammatory bowel disease.<ref>{{cite journal | vauthors = Cho JH, Nicolae DL, Ramos R, Fields CT, Rabenau K, Corradino S, Brant SR, Espinosa R, LeBeau M, Hanauer SB, Bodzin J, Bonen DK | title = Linkage and linkage disequilibrium in chromosome band 1p36 in American Chaldeans with inflammatory bowel disease | journal = Human Molecular Genetics | volume = 9 | issue = 9 | pages = 1425–1432 | date = May 2000 | pmid = 10814724 | doi = 10.1093/hmg/9.9.1425 | doi-access = free }}</ref> Some of the putative regions encode transporter proteins such as [[OCTN1]] and [[OCTN2]]. Other potential regions involve cell scaffolding proteins such as the [[Membrane-associated guanylate kinase|MAGUK family]]. [[Human leukocyte antigen]] associations may even be at work. In fact, this linkage on chromosome 6 may be the most convincing and consistent of the genetic candidates.<ref name=Baumgart/>

Multiple autoimmune disorders are associated with ulcerative colitis, including [[celiac disease]],<ref name=Shah_Celiac>{{cite journal | vauthors = Shah A, Walker M, Burger D, Martin N, von Wulffen M, Koloski N, Jones M, Talley NJ, Holtmann GJ | title = Link Between Celiac Disease and Inflammatory Bowel Disease | journal = Journal of Clinical Gastroenterology | volume = 53 | issue = 7 | pages = 514–522 | date = August 2019 | pmid = 29762265 | doi = 10.1097/MCG.0000000000001033 | s2cid = 44102071 }}</ref> [[psoriasis]],<ref>{{cite journal | vauthors = Fu Y, Lee CH, Chi CC | title = Association of Psoriasis With Inflammatory Bowel Disease: A Systematic Review and Meta-analysis | journal = JAMA Dermatology | volume = 154 | issue = 12 | pages = 1417–1423 | date = December 2018 | pmid = 30422277 | pmc = 6583370 | doi = 10.1001/jamadermatol.2018.3631 }}</ref> [[lupus erythematosus]],<ref>{{cite journal | vauthors = Katsanos KH, Voulgari PV, Tsianos EV | title = Inflammatory bowel disease and lupus: a systematic review of the literature | journal = Journal of Crohn's & Colitis | volume = 6 | issue = 7 | pages = 735–742 | date = August 2012 | pmid = 22504032 | doi = 10.1016/j.crohns.2012.03.005 | doi-access = free }}</ref> [[rheumatoid arthritis]],<ref name=Chen_RA>{{cite journal | vauthors = Chen Y, Chen L, Xing C, Deng G, Zeng F, Xie T, Gu L, Yang H | title = The risk of rheumatoid arthritis among patients with inflammatory bowel disease: a systematic review and meta-analysis | journal = BMC Gastroenterology | volume = 20 | issue = 1 | pages = 192 | date = June 2020 | pmid = 32552882 | pmc = 7301504 | doi = 10.1186/s12876-020-01339-3 | doi-access = free }}</ref> [[episcleritis]], and [[scleritis]].<ref name=Troncoso /> Ulcerative colitis is also associated with [[acute intermittent porphyria]].<ref>{{cite journal | vauthors = Sieg I, Beckh K, Kersten U, Doss MO | title = Manifestation of acute intermittent porphyria in patients with chronic inflammatory bowel disease | journal = Zeitschrift für Gastroenterologie | volume = 29 | issue = 11 | pages = 602–605 | date = November 1991 | pmid = 1771936 }}</ref>