肠道糖苷酶缺乏症
中文名称
通路描述
此处注释了两种肠道消化所需酶缺陷导致的疾病：乳糖酶（LCT，乳糖 - 菲洛林水解酶蛋白的亚基）和蔗糖异构酶（SI）。前者影响乳儿，后者影响断乳后的个体。乳糖是母乳的主要成分。乳儿要从肠道吸收乳糖，必须首先由小肠绒毛上皮细胞外表面微绒毛上的乳糖酶将其水解。破坏乳糖酶活性的突变与新生儿急性疾病相关，因为肠道细菌发酵乳糖会导致严重腹泻。该疾病通过给受影响的婴儿喂食无乳糖配方粉得到有效治疗。这种先天性疾病与许多人类人群在断乳后 LCT 表达下调导致的较轻形式的乳糖不耐受不同（Jarvela et al. 2009）。断乳后的饮食中的淀粉由淀粉酶分解为二糖和寡糖，必须进一步分解为单糖才能被小肠上皮细胞刷状缘的 endothelial 细胞吸收。如果未被消化，肠上皮细胞关联的 SI 起关键作用，它们将留在肠道腔内并被肠道细菌发酵，导致渗透性和发酵性腹泻（Naim et al. 2012; Van Beers et al. 1995）。
英文描述
Intestinal saccharidase deficiencies Defects in in two enzymes required for intestinal digestion of dietary carbohydrate, lactase (LCT, a domain of lactase-phlorizin hydrolase protein) and sucrase-isomaltase (SI), are annotated here. The first affects nursing infants; the second affects individuals after weaning.The disaccharide lactose is a major constituent of human breast milk. To be taken up from the gut in the nursing infant, this sugar must first be hydrolyzed by LCT present on the external face of enterocytes in microvilli of the small intestine. Mutations that disrupt LCT activity are associated with acute illness in newborn children as lactose fermentation by gut bacteria leads to severe diarrhea. The condition is effectively treated by feeding affected infants a lactose-free formula. This congenital disease is distinct from the down-regulation of LCT expression after weaning in many human populations that is associated with a milder form of lactose intolerance in adults (Jarvela et al. 2009).The starch in a post-weaning diet is digested by amylases to di- and oligosaccharides that must be further digested to monosaccharides in order to be taken up from the lumen of the small intestine into endothelial cells of the intestinal brush border. If they are not digested, a process in which enterocyte-associated SI plays a central role, they remain in the gut lumen and are fermented by gut bacteria, leading to osmotic and fermentative diarrhea (Naim et al. 2012; Van Beers et al. 1995).
所含基因
1 个基因