Hereditary fructose intolerance (IHF) is an autosomal recessive disorder of fructose metabolism , produced by deficiency of hepatic 1-phosphate aldolase fructose activity leading to gastrointestinal disorders and postprandial hypoglycemia following fructose intake. IHF is a benign condition when treated, but it is life-threatening and potentially fatal in the absence of treatment.
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- 1 Epidemiology
- 2 Clinical description
- 3 Etiology
- 4 Diagnostic methods
- 1 Differential diagnosis
- 2 Prenatal diagnosis
- 5 Genetic advice
- 6 Management and treatment
- 7 Forecast
- 8 Sources
The prevalence has been estimated to be 1 in 20,000 in Europe , with the carrier frequency being around 1 in 70. The prevalence of IHF in the adult population is unknown.
IHF occurs during lactation at weaning (when fructose is incorporated into the diet ), manifesting with hypoglycemia , lactic acidosis , ketosis with recurrent vomiting , abdominal pain , and systemic manifestations after consumption of foods containing fructose. A persistent intake of fructose and related sugars (such as sucrose and sorbitol ) can lead to growth retardation, hepatomegaly , proximal tubular dysfunction, liver and kidney failure, seizures, comaand risk of death. All those who reach adulthood develop a natural aversion to fruits and sweets and describe a long lifetime history of vomiting and hypoglycemia after fructose ingestion. Dental caries is absent in a significant proportion of the adult population with IHF (which may be indicative of the diagnosis). Sometimes the diagnosis can be made in an adult who, because of his aversion to fructose, has rejected all foods containing it since childhood .
This condition occurs when the body lacks an enzyme called aldolase B. This substance is needed to break down fructose . If a person eats or not containing fructose or sucrose ( sugar cane or sugar beet or sugar), complex chemical changes occur in the body. The body cannot transform the form of sugar it stores ( glycogen ) into glucose . Consequently, blood sugar decreases and dangerous substances accumulate in the liver.. IHF is caused by mutations in the ALDOB gene (9q22.3), which encodes the enzyme aldolase B. Affected individuals are unable to fully metabolize fructose in the liver, intestine, and kidneys due to fructose deficiency 1- phosphate aldolase B, resulting in an accumulation of the substrate fructose 1-phosphate and the subsequent depletion of adenosine triphosphate.
Early diagnosis is essential, as those affected can enjoy a symptom-free life by eliminating fructose from their diet . When clinical features and nutritional and family history are suggestive, IHF is confirmed by molecular diagnosis from peripheral leukocyte DNA . Exceptionally, when no mutation is identified, a liver biopsy can be performed to assess aldolase B activity.
Differential diagnosis includes pyloric stenosis, gastroesophageal reflux, galactosemia , tyrosinemia, glycogen storage disease , ornithine transcarbamylase deficiency, Wilson’s disease , hematopoietic and lymphoid tissue tumors, and fructose malabsorption.
Prenatal diagnosis is technically possible in families with known mutations, but is not indicated due to the benign nature of this condition.
IHF is an autosomal recessive condition.
Management and treatment
Suspecting IHF, fructose should be excluded from the diet . This implies avoiding all kinds of foods that contain fructose , sucrose and / or sorbitol , either naturally or added during processing, including certain pharmacological preparations and infant formulas. Typically, the beneficial clinical and chemical effects of fructose restriction are seen within a few days. Multivitamin preparations can be prescribed to supply vitamin deficiencies, especially vitamin C and folates . In case of acute poisoning, intensive care and support measures may be required.