Fructosemia, hereditary

Hereditary Fructose Intolerance
[[File:|250px|]]
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Hypoglycemia, abdominal pain, vomiting
Complications	N/A
Onset	Infancy
Duration	Lifelong
Types	N/A
Causes	Aldolase B deficiency
Risks	N/A
Diagnosis	Genetic testing, liver biopsy
Differential diagnosis	N/A
Prevention	N/A
Treatment	Fructose-free diet
Medication	N/A
Prognosis	N/A
Frequency	Rare
Deaths	N/A

Hereditary Fructose Intolerance (HFI) is a rare genetic disorder characterized by the inability to metabolize fructose, a simple sugar found in many foods. This condition is caused by a deficiency of the enzyme aldolase B, which is crucial for the proper breakdown of fructose in the liver, kidneys, and intestines.

Pathophysiology

In individuals with hereditary fructose intolerance, the deficiency of aldolase B leads to the accumulation of fructose-1-phosphate in the liver. This accumulation inhibits the breakdown of glycogen and the synthesis of glucose, resulting in severe hypoglycemia and other metabolic disturbances. The toxic effects of fructose-1-phosphate also cause liver and kidney damage over time.

Genetics

Hereditary fructose intolerance is inherited in an autosomal recessive pattern, meaning that an affected individual must inherit two copies of the defective gene, one from each parent. The gene responsible for HFI is located on chromosome 9 and is known as the ALDOB gene. Mutations in this gene lead to the production of a nonfunctional aldolase B enzyme.

Symptoms

Symptoms of hereditary fructose intolerance typically appear when an infant begins to consume foods containing fructose, sucrose, or sorbitol. Common symptoms include:

• Severe abdominal pain
• Vomiting
• Hypoglycemia
• Jaundice
• Failure to thrive
• Hepatomegaly (enlarged liver)

If left untreated, HFI can lead to serious complications such as liver failure, kidney damage, and even death.

Diagnosis

Diagnosis of hereditary fructose intolerance can be challenging due to its rarity and the nonspecific nature of its symptoms. It is often suspected based on clinical history and dietary patterns. Confirmatory tests include:

• Genetic testing to identify mutations in the ALDOB gene
• Liver biopsy to assess enzyme activity (less commonly used due to invasiveness)

Management

The primary treatment for hereditary fructose intolerance is a strict avoidance of fructose, sucrose, and sorbitol in the diet. This involves careful reading of food labels and awareness of hidden sources of these sugars. With proper dietary management, individuals with HFI can lead healthy lives without significant complications.

Prognosis

With early diagnosis and strict adherence to a fructose-free diet, individuals with hereditary fructose intolerance can have a normal life expectancy and quality of life. However, accidental ingestion of fructose can lead to acute episodes of hypoglycemia and other metabolic disturbances.

Also see

• Fructose malabsorption
• Galactosemia
• Glycogen storage disease
• Metabolic disorder