Binder V
Department of Medical Gastroenterology, Herlev Hospital, University of Copenhagen, Herlev, Denmark.
Dig Dis. 1998 Nov-Dec;16(6):351-5. doi: 10.1159/000016891.
Family studies of different designs have been carried out in the last few years. Five to ten percent of patients have another case of inflammatory bowel disease (IBD) among their first-degree relatives, with about 75-80% concordance for the same disease within the family. About 20% of multi-affected families present both cases with ulcerative colitis and Crohn's disease. The population relative risk in first-degree relatives of patients show a 14-15 times higher prevalence of IBD. Prevalence values of 1.5-3.5% in first-degree relatives have been found, with an even higher calculated lifetime risk especially in offspring and siblings of patients with IBD. Earlier disease onset in offspring of patients with IBD have consistently been found, and genetic anticipation has been hypothesized. The phenomenon, however, may be a result of a combination of a time trend - increasing the incidence of Crohn's disease - and the fact that patients with early onset of IBD may have lower fertility and therefore may be underrepresented in the parent-child pairs studied. Twin studies have shown significantly higher concordance rates in monozygotic than in dizygotic twins. Further, the concordance rate in monozygotic twins is higher in Crohn's disease than in ulcerative colitis, indicating a stronger genetic influence in this condition. Disease course and prognosis within families have been studied without convincing concordance found in this respect among family members.
在过去几年中开展了不同设计的家系研究。5%至10%的患者在其一级亲属中有另一例炎症性肠病（IBD），同一疾病在家族中的一致性约为75%至80%。约20%的多病例家庭中同时出现溃疡性结肠炎和克罗恩病病例。患者一级亲属中的人群相对风险显示IBD患病率高出14至15倍。已发现一级亲属中的患病率值为1.5%至3.5%，计算得出的终生风险甚至更高，尤其是IBD患者的后代和兄弟姐妹。一直发现IBD患者的后代发病更早，并有人提出了遗传早现的假设。然而，这种现象可能是时间趋势（克罗恩病发病率增加）与IBD早发患者可能生育力较低因此在研究的亲子对中代表性不足这一事实共同作用的结果。双生子研究显示，同卵双胞胎的一致性率显著高于异卵双胞胎。此外，同卵双胞胎中克罗恩病的一致性率高于溃疡性结肠炎，表明这种疾病的遗传影响更强。已对家族内的疾病病程和预后进行了研究，但在这方面家庭成员之间未发现令人信服的一致性。
