Disaccharidase Deficiency

Key Features

• Characteristics of primary disaccharidase deficiency include

  • Permanent disaccharide intolerance

  • Absence of intestinal injury

  • Frequent positive family history

• Transient secondary disaccharidase deficiency may be caused by mucosal damage, such as from acute viral enteritis

• Genetic lactase deficiency develops in

  • Virtually all Asians, Alaskan natives, and Native Americans

  • 80% of Africans

  • 70% of African Americans

  • 30–60% of white Americans

• Congenital lactase deficiency is extremely rare

• Sucrase-isomaltase deficiency

  • Inherited in an autosomal recessive fashion

  • Most common in Greenland, Iceland, and among Alaskan natives

  • Condition is rare in other groups

Clinical Findings

• Lactase deficiency

  • Variable degrees of diarrhea

  • Abdominal distention

  • Flatus

  • Abdominal pain

• Sucrase-isomaltase deficiency

  • Abdominal distention

  • Failure to thrive

  • Watery, acidic diarrhea

Diagnosis

• Lactase deficiency

  • Stools are liquid or frothy and acidic

  • May test positive for reducing substances

  • Diagnostic tests include genetic testing and lactose breath test

• Sucrase-isomaltase deficiency

  • Because sucrose is not a reducing sugar, stool may test negative for reducing substances unless the sucrose is hydrolyzed by colon bacteria

  • Diagnosis is made by oral sucrose breath hydrogen testing (1 g/kg), or by testing a snap frozen intestinal biopsy for enzyme activity

  • Partial enzyme deficiencies exist

Treatment

• Lactase deficiency

  • Dietary avoidance of lactose or with lactase supplementation

  • Transient or secondary lactase deficiency caused by mucosal injury such as an acute viral gastroenteritis resolves within a few weeks

• Sucrase-isomaltase deficiency

  • Avoidance of sucrose and starches rich in amylopectin

  • Use of sacrosidase enzyme supplement