Glucose-galactose malabsorption in an adult: perfusion studies of sugar, electrolyte, and water transport

Long-Term Dietary Changes in Subjects with Glucose Galactose Malabsorption Secondary to Biallelic Mutations of SLC5A1

BACKGROUND

Glucose galactose malabsorption (GGM) is a congenital diarrheal disorder of intestinal Na+/glucose cotransport (SGLT1/SLC5A1). The required glucose and galactose-restricted diet has been well described in infancy, but long-term nutrition follow-up is limited.

AIM

To perform a comprehensive nutritional assessment on a cohort of patients with GGM to gain insights into the consumption patterns within the population.

METHODS

A cross-sectional study examining dietary intake of a GGM cohort using prospective food records. The calories and nutrients of all foods, beverages, and condiments were analyzed with descriptive statistics and compared to intake patterns of age- and sex-matched NHANES groups.

RESULTS

The six patients were 0.7-26 years old. Whole foods and vegetable fats were major parts of the diet, while dairy and added sweeteners were restricted. Compared to typical US intakes, mean macronutrient distribution was 88th percentile from fat, 18th percentile from carbohydrates, and 78th percentile from protein. Fructose consumption, as a proportion of total sugar intake, decreased with age, from 86.1 to 50.4%. Meanwhile, glucose consumption increased with age, from 13.8 to 48.6% of sugar intake. However, the actual amount of glucose consumed remained low, equivalent to 4th percentile of US consumption level. Galactose intake was marginal throughout life.

CONCLUSIONS

A GGM diet is a high-fat and high-protein/low-carbohydrate diet that is rich in fruits and vegetables but limited in dairy and added sugar. Relatively less fructose but more glucose is incorporated into the diet with age. Future studies should investigate the effects of the GGM diet on gut microbiome and long-term health.

[Neonatal diarrhea due to congenital glucose-galactose malabsorption: report of seven cases]

Congenital glucose-galactose malabsorption (CGGM) is a rare autosomal recessive disorder, which presents as a protracted diarrhea in early neonatal life. We describe the clinical history, diagnostic evaluation, and management of 7 children with CGGM in western France. There were 4 girls and 3 boys from 5 families, born between 1984 and 2010. The principal complaint was a neonatal onset of watery and acidic severe diarrhea complicated by hypertonic dehydration. The diarrhea stopped with fasting. In 2 cases, the family history supported the diagnosis. In the other cases, elimination of glucose and galactose (lactose) from the diet resulted in the complete resolution of diarrhea symptoms. In 2 cases, the H2 breath tests were positive. In 2 cases, the HGPO or oral glucose tolerance test (OGTT) demonstrated an abnormal curve with glucose and a normal curve with fructose. DNA sequencing was not used. When glucose and galactose were eliminated from the diet, the infants had normal growth and development. In conclusion, CGGM is a rare etiology of neonatal diarrhea; however, the diagnosis is easy to make and the prognosis is excellent.

Nutrition management of congenital glucose-galactose malabsorption: a case study

In this article we describe the clinical history, diagnostic evaluation, and management of an infant who had congenital glucose-galactose malabsorption (CGGM)--a rare disorder thought to be inherited as an autosomal recessive trait. Because of defective sodium-coupled cotransport of glucose and galactose in the intestinal mucosa, infants with CGGM suffer from chronic, profuse, watery diarrhea that often leads to hypertonic dehydration. This infant experienced persistent diarrhea and hypernatremic dehydration during the first 3 months of life. Despite management with elemental formulas and continuous nasogastric feedings during initial hospitalizations, worsening diarrhea and dehydration persisted and malnutrition occurred. Diagnostic evaluations ruled out cystic fibrosis and bacterial or viral gastroenteritis. Diagnostic tests also revealed normal pancreatic exocrine function and normal villus architecture. The persistence of glucose-positive, watery diarrhea, even when the infant was fed an oral electrolyte solution, led to the diagnosis of CGGM. The infant was treated successfully with a carbohydrate-free infant formula to which fructose was added incrementally to meet energy requirements. Parental education about dietary management of CGGM with specialized formula supplemented with fructose and solid food feedings was an important component of this infant's nutrition therapy. Aggressive nutrition intervention for the infants and judicious dietary counseling for parents can lead to normal growth and neurological development for an infant with CGGM.

Prenatal identification of a heterozygous status in two fetuses at risk for glucose-galactose malabsorption

Glucose-galactose malabsorption (GGM) is an autosomal recessive disorder which presents with severe osmotic diarrhoea shortly after birth. Two proband siblings with GGM were previously demonstrated to contain a missense mutation (D28N) in the Na(+)-dependent glucose/galactose cotransporter (SGLT1) that accounts for the defect in sugar absorption. Prenatal screening for GGM was performed in two subsequent pregnancies in this large consanguineous family. The first exon of the SGLT1 gene was PCR-amplified from genomic DNA and screened for the presence of the D28N mutation by EcoRV restriction digestion. The proband's sibling was heterozygous and a cousin was not a carrier of the D28N mutation. Both children at 2-years of age remain healthy and have had no diarrhoeal symptoms. Molecular biology techniques will allow a prospective determination of the presence of an abnormal SGLT1 allete and potentially decrease the postnatal morbidity.

Glucose transport during ageing by human intestinal brush-border membrane vesicles

Glucose absorption by the small intestine is a complex phenomenon, that can be successfully studied by means of isolated brush-border and basolateral membrane vesicles of the enterocytes. We have carried out transport experiments on isolated brush-border membrane vesicles from the human small intestine, taking into account the age of the subjects. Our studies demonstrated that Na+-glucose cotransporter activity decreased as age increased with the "overshoot" phenomenon disappearing altogether in the oldest subjects. This effect was compared to that observed in intestinal membrane vesicles of young patients suffering from Crohn's disease; in this case there was a marked decrease in the Na+-dependent D-glucose uptake, but the "overshoot", even though low, was present. K+-dependent D-glucose transport, diffusion of L-glucose and the levels of some enzyme markers for intestinal brush-border membranes were also studied.

Glucose-galactose malabsorption: demonstration of specific jejunal brush border membrane defect

Jejunal brush border glucose transport was studied in a patient with glucose-galactose malabsorption and in controls, using jejunal brush border membrane vesicles (BBMV) prepared from conventional jejunal biopsies. Whereas BBMV from controls showed a seven-fold enhancement of D-glucose uptake in the presence of an inwardly directed sodium gradient compared with its absence, no such enhancement was seen in the patient's vesicles. In BBMV from the patient, initial D-glucose uptake under sodium gradient conditions was only 10% of the mean control value. In contrast, sodium/proton exchange in BBMV from the patient was intact. These data provide the first unequivocal evidence that the jejunal brush border membrane is the site of a specific defect in sodium dependent glucose transport in glucose-galactose malabsorption. Measurement of glucose uptake by BBMV may well be the optimal diagnostic technique in this disorder.

Aboral changes in D-glucose transport by human intestinal brush-border membrane vesicles

D-Glucose transport was investigated in isolated brush-border membrane vesicles from human small intestine. Characteristics of D-glucose transport from the jejunum were compared with that in the mid and terminal ileum. Jejunal and mid-ileal D-glucose transport was Na+-dependent and electrogenic. The transient overshoot of jejunal D-glucose transport was significantly greater than corresponding values in mid-ileum. The terminal ileum did not exhibit Na+-dependent D-glucose transport, but did exhibit Na+-dependent taurocholate transport. Na+-glucose co-transport activity as measured by tracer-exchange experiments was greatest in the jejunum, and diminished aborally. We conclude that D-glucose transport in man is Na+-dependent and electrogenic in the proximal intestine and directly related to the activity of D-glucose-Na+ transporters present in the brush-border membranes. D-Glucose transport in the terminal ileum resembles colonic transport of D-glucose.

Intestinal adaptation after jejuno-ileal bypass operation for massive obesity

Intestinal adaptation was studied in six patients with massive obesity treated by jejuno-ileal bypass operation. Glucose absorption in the jejunum was measured by a perfusion technique. The morphometric and enzymatic measurements were carried out on biopsies from the proximal jejunum and the distal ileum. Results obtained before and six months after the operation were compared. The glucose absorption per unit length of jejunum was unchanged at a glucose concentration of 66 mmol/l in the perfusate but increased significantly at a glucose concentration of 133 mmol/l (p less 0.025). The mean sucrase activity did not change, whereas the lactase activity increased significantly in the jejunum and ileum. The mean villus height increased significantly, while the epithelial cell height and cell width were unchanged both in the jejunum and the ileum, suggesting that the operation resulted in epithelial cell hyperplasia. The glucose absorption in the jejunum was positively correlated with the villus height (r = 0.76), which suggests that the increased glucose absorption was related to an increased number of epithelial cells.