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Hereditary Fructose Intolerance.

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GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2019.
2015 Dec 17.

Author information

1
Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, Colorado
2
Royal United Hospitals Bath, NHS Foundation Trust, Bath, United Kingdom
3
Children's Hospital Colorado, Aurora, Colorado

Excerpt

CLINICAL CHARACTERISTICS:

Following dietary exposure to fructose, sucrose, or sorbitol, untreated hereditary fructose intolerance (HFI) is characterized by metabolic disturbances (hypoglycemia, lactic acidemia, hypophosphatemia, hyperuricemia, hypermagnesemia, hyperalaninemia) and clinical findings (nausea, vomiting, and abdominal distress; chronic growth restriction/failure to thrive). Untreated HFI typically first manifests when fructose- and sucrose-containing foods are introduced in the course of weaning young infants from breast milk. If large quantities of fructose are ingested, the infant may acutely develop lethargy, seizures, and/or progressive coma. Untreated HFI may result in renal and hepatic failure. If identified and treated before permanent organ injury occurs, individuals with HFI can experience a normal quality of life and life expectancy.

DIAGNOSIS/TESTING:

The diagnosis of HFI is established in a proband (with suggestive metabolic disturbances and clinical findings following dietary exposure to fructose, sucrose, or sorbitol) who has demonstrated either biallelic pathogenic variants in ALDOB on molecular genetic testing or deficient hepatic fructose 1-phosphate aldolase (aldolase B) activity on liver biopsy.

MANAGEMENT:

Treatment of manifestations: Acute manifestations (e.g., lethargy, seizures, or progressive coma and/or renal and hepatic failure) should be managed symptomatically in a hospital setting, including intravenous glucose (dextrose) administration, supportive treatment of hepatic insufficiency, and treatment of metabolic acidosis, if present. Prevention of primary manifestations: Dietary restriction of fructose, sucrose, and sorbitol is the cornerstone of HFI treatment. Specific agents to be avoided include fructose, high-fructose corn syrup, honey, agave syrup, inverted sugar, maple-flavored syrup, molasses, palm or coconut sugar, and sorghum. In addition, medicines and formulas in which fructose/sucrose may not be listed as a primary component need to be avoided; examples include syrups, enema solutions, some immunoglobulin solutions, and many infant and pediatric nutritional drinks. During hospitalizations special caution is advised to avoid use of fructose-containing intravenous fluids. Prevention of secondary complications: Given that reduced fruit and vegetable intake is a dietary requirement, daily supplementation with a "sugar-free" multivitamin is recommended to prevent micronutrient deficiencies, specifically water-soluble vitamins. Surveillance: No formal guidelines for surveillance exist. Once the diagnosis of HFI has been made, periodic evaluation of liver function, renal function, and growth is reasonable, particularly if compliance with the fructose/sucrose/sorbitol-restricted diet is not absolute. Agents/circumstances to avoid: Enteral or parenteral exposure to fructose, sorbitol, sucrose, sucralose, and polysorbate. Fructose tolerance testing ("fructose challenge") in the diagnosis of HFI. Evaluation of relatives at risk: Presymptomatic diagnosis and treatment is warranted for sibs at risk in order to avoid life-threatening complications by restriction of fructose intake as soon as possible.

GENETIC COUNSELING:

HFI is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being a carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if both ALDOB pathogenic variants have been identified in an affected family member.

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