Glucose/galactose malabsorption (GGM) is a rare autosomal recessive disorder caused by a defect in glucose and galactose transport across the intestinal brush border. Patients with GGM present with neonatal onset of severe life-threatening watery diarrhea and dehydration. If diagnosed and treated properly, patients can fully recover and show normal growth and development (summary by Xin and Wang, 2011).

Mitochondrial neurogastrointestinal encephalopathy (MNGIE) disease is characterized by progressive gastrointestinal dysmotility (manifesting as early satiety, nausea, dysphagia, gastroesophageal reflux, postprandial emesis, episodic abdominal pain and/or distention, and diarrhea); cachexia; ptosis/ophthalmoplegia or ophthalmoparesis; leukoencephalopathy; and demyelinating peripheral neuropathy (manifesting as paresthesias (tingling, numbness, and pain) and symmetric and distal weakness more prominently affecting the lower extremities). The order in which manifestations appear is unpredictable. Onset is usually between the first and fifth decades; in about 60% of individuals, symptoms begin before age 20 years.