Congenital intestinal disease due to an enzymatic defect
-Rare gastroenterologic disease
-Rare genetic disease
Disorder of carbohydrate absorption and transport
-Rare genetic disease
Congenital lactase deficiency is a severe gastrointestinal disorder characterized by watery diarrhea in infants fed with breast milk or other lactose-containing formulas.
In disaccharide intolerance II, cellobiose intolerance would be expected as well as that for lactose. Sucrose, maltose, and starch are well tolerated. In a breastfed infant who developed watery diarrhea on the third day of life, Levin et ... In disaccharide intolerance II, cellobiose intolerance would be expected as well as that for lactose. Sucrose, maltose, and starch are well tolerated. In a breastfed infant who developed watery diarrhea on the third day of life, Levin et al. (1970) demonstrated absent lactase in a specimen of duodenal mucosa which was histologically normal and showed normal maltase isomaltase and sucrase activities. Convincing direct demonstration of absent lactase in biopsies obtained in infancy has been achieved only twice before, according to the authors. A sister of the proband was probably identically affected. Savilahti et al. (1983) reported 16 Finnish cases (10 male, 6 female) discovered during the previous 17 years. In each case the mother noted watery diarrhea, generally after the first feed of breast milk but at the latest by age 10 days. The 16 cases included 4 pairs of sibs. With the virtual disappearance of diarrhea as a cause of death in the first year of life, the authors believed that every case of congenital lactase deficiency in their population was discovered. Segregation analysis, assuming complete ascertainment, showed agreement with the number expected. The Finnish collection of 16 patients was especially impressive in light of the fact that only 18 cases had been reported elsewhere. The late consequences of this genetic disorder were not fully known. Affected persons might have less atherosclerosis than the average because they avoid dairy products, just as persons with fructose intolerance (229600) have fewer dental caries. Jarvela et al. (1998) stated that, since 1966, 42 patients with congenital lactase deficiency had been diagnosed in Finland. In this disorder an almost total lack of lactase-phlorizin hydrolase activity is found in jejunal biopsy material. In adult-type hypolactasia (223100), the most common genetic enzyme deficiency in humans, this enzyme activity is reduced to 5 to 10%. Congenital lactose intolerance is probably a different disorder related to gastric absorption of lactose and lactosuria.
Poggi and Sebastio (1991) sequenced the exons, the exon-intron boundaries, and the promoter region of the lactase gene of a Finnish patient with congenital lactase deficiency. No mutation leading to a missense, frameshift, or other change in amino ... Poggi and Sebastio (1991) sequenced the exons, the exon-intron boundaries, and the promoter region of the lactase gene of a Finnish patient with congenital lactase deficiency. No mutation leading to a missense, frameshift, or other change in amino acid sequence was found. They raised the question of a defect in a control mechanism 'in trans' as the basis of the abnormality. Enattah et al. (2002) identified 2 variants upstream from the LCT gene (see 601806.0001-601806.0002) that were completely associated with hypolactasia of the adult type (223100). However, no association was found between these variants and congenital lactase deficiency in 19 Finnish families. In patients with congenital lactase deficiency, Kuokkanen et al. (2006) identified 5 distinct mutations in the coding region of the LCT gene. In 27 of 32 patients (84%), they found homozygosity for a nonsense mutation, 4170T-A (Y1390X; 603202.0001), designated 'Fin(major).' In the other patients, they identified compound heterozygosity. The data demonstrated that, in contrast to adult-type hypolactasia (lactose intolerance) caused by a variant of the regulatory element, the severe infancy type represents the outcome of mutations affecting the structure of the protein with inactivation of the enzyme.