Summary about Disease
Fructosemia, also known as hereditary fructose intolerance (HFI), is a rare inherited metabolic disorder characterized by a deficiency in the enzyme aldolase B. This enzyme is crucial for breaking down fructose, a type of sugar found in fruits, honey, and some vegetables. Without functional aldolase B, fructose-1-phosphate accumulates in the liver, kidneys, and intestines, leading to cellular damage and organ dysfunction.
Symptoms
Symptoms of HFI typically appear after the introduction of fructose or sucrose (which is broken down into fructose and glucose) into an infant's diet. Common symptoms include:
Vomiting
Poor feeding/aversion to sweet foods
Lethargy/irritability
Jaundice
Failure to thrive/poor weight gain
Abdominal pain/distension
Liver enlargement (hepatomegaly)
Kidney dysfunction
Seizures
Coma (in severe cases)
Causes
HFI is caused by mutations in the ALDOB gene, which provides instructions for making the aldolase B enzyme. It is an autosomal recessive disorder, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. Individuals with only one copy of the mutated gene are carriers and usually do not exhibit symptoms.
Medicine Used
4. Medicine used There is no specific medication to "cure" HFI. The primary treatment involves strict dietary management. Medical interventions focus on managing complications and providing supportive care:
Dietary Management: Avoiding all sources of fructose, sucrose, and sorbitol is crucial. This includes careful reading of food labels and avoiding fruits, honey, cane sugar, table sugar, high-fructose corn syrup, and many processed foods.
Intravenous Fluids: May be needed to correct dehydration and electrolyte imbalances during acute episodes.
Medications to manage complications: If liver damage occurs, medications for liver support might be used. Similarly, treatments for kidney problems may be needed if kidney function is affected.
Is Communicable
No, HFI is not communicable. It is a genetic disorder and cannot be spread from person to person.
Precautions
The most important precaution is strict adherence to a fructose-free, sucrose-free, and sorbitol-free diet. Specific precautions include:
Careful Food Label Reading: Always check ingredient lists for hidden sources of fructose, sucrose, and sorbitol.
Consultation with a Dietitian: Working with a registered dietitian is essential to develop a safe and nutritionally adequate diet.
Medical Alert Bracelet: Wearing a medical alert bracelet can inform healthcare professionals about the condition in case of an emergency.
Awareness of Medications: Be aware that some medications and cough syrups may contain sucrose or sorbitol as inactive ingredients.
Emergency Plan: Have a plan in place for managing accidental fructose ingestion.
How long does an outbreak last?
HFI does not have "outbreaks" in the typical sense. The symptoms are triggered by the ingestion of fructose, sucrose, or sorbitol. The duration of symptoms depends on the amount of offending sugar consumed and the individual's ability to clear it from their system. Acute episodes can last for several hours to days.
How is it diagnosed?
Diagnosis typically involves:
Clinical Evaluation: Assessment of symptoms and medical history.
Urine test: Can be used to detect reducing sugars in urine after fructose ingestion.
Enzyme Assay: Measurement of aldolase B activity in a liver biopsy sample (rarely performed due to invasive nature).
Genetic Testing: DNA analysis to identify mutations in the ALDOB gene. This is the most common and preferred diagnostic method.
Timeline of Symptoms
9. Timeline of symptoms The timeline of symptoms varies depending on the individual and the amount of fructose consumed. However, a general timeline looks like this:
Infancy (after fructose introduction):
Vomiting, poor feeding, irritability, lethargy
Jaundice
Failure to thrive
Abdominal distention
Childhood/Adulthood (with fructose ingestion):
Nausea, abdominal pain
Hypoglycemia (low blood sugar)
Liver and kidney dysfunction (if repeated exposure)
Long-term/Untreated:
Liver cirrhosis
Kidney failure
Developmental delays (in children)
Important Considerations
Early Diagnosis is Crucial: Early diagnosis and dietary management are essential to prevent long-term complications.
Lifelong Dietary Restrictions: The dietary restrictions are lifelong.
Genetic Counseling: Genetic counseling is recommended for families with a history of HFI.
Nutritional Adequacy: Ensuring adequate nutrition while adhering to dietary restrictions is important. A registered dietitian can help create a balanced meal plan.
Regular Monitoring: Regular monitoring of liver and kidney function is important to detect and manage any complications.