Congenital maltase-glucoamylase deficiency associated with lactase and sucrase deficiencies

J Pediatr Gastroenterol Nutr. 2002 Oct;35(4):573-9. doi: 10.1097/00005176-200210000-00022.


Background: Multiple enzyme deficiencies have been reported in some cases of congenital glucoamylase, sucrase, or lactase deficiency. Here we describe such a case and the investigations that we have made to determine the cause of this deficiency.

Methods and results: A 2.5 month-old infant, admitted with congenital lactase deficiency, failed to gain weight on a glucose oligomer formula (Nutramigen). Jejunal mucosal biopsy at 4 and 12 months revealed normal histology with decreased maltase-glucoamylase, sucrase-isomaltase, and lactase-phlorizin hydrolase activities. Testing with a C-starch/breath CO loading test confirmed proximal starch malabsorption. Sequencing of maltase-glucoamylase cDNA revealed homozygosity for a nucleotide change (C1673T) in the infant, which causes an amino acid substitution (S542L) 12 amino acids after the N-terminal catalytic aspartic acid. The introduction of this mutation into "wildtype" N-terminus maltase-glucoamylase cDNA was not associated with obvious loss of maltase-glucoamylase enzyme activities when expressed in COS 1 cells and this amino-acid change was subsequently found in other people. Sequencing of the promoter region revealed no nucleotide changes. Maltase-glucoamylase, lactase, and sucrase-isomaltase were each normally synthesized and processed in organ culture.

Conclusions: The lack of evidence for a causal nucleotide change in the maltase-glucoamylase gene in this patient, and the concomitant low levels of lactase and sucrase activity, suggest that the depletion of mucosal maltase-glucoamylase activity and starch digestion was caused by shared, pleiotropic regulatory factors.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Breath Tests
  • Carbohydrate Metabolism, Inborn Errors / enzymology*
  • Carbohydrate Metabolism, Inborn Errors / genetics
  • DNA, Complementary / chemistry
  • DNA, Complementary / genetics
  • Humans
  • Infant
  • Intestinal Absorption
  • Intestinal Mucosa / enzymology*
  • Intestinal Mucosa / pathology
  • Lactase
  • Male
  • Microvilli / enzymology
  • Starch / metabolism
  • Sucrase / deficiency*
  • Sucrase / genetics
  • alpha-Glucosidases / deficiency*
  • alpha-Glucosidases / genetics
  • beta-Galactosidase / deficiency*
  • beta-Galactosidase / genetics


  • DNA, Complementary
  • Starch
  • Lactase
  • alpha-Glucosidases
  • beta-Galactosidase
  • Sucrase