What Is Hereditary Fructose Intolerance (HFI)?
Hereditary fructose intolerance (HFI)is a disorder caused by mutations in the ALDOB gene that is characterized by an inability to break down fructose, a common sugar found in fruit and many other foods. When an individual with HFI consumes fructose, the result is low blood sugar (hypoglycemia) and a buildup of toxic substances in the liver.
The first symptoms of HFI usually appear when a child is first introduced to formula or foods containing fructose or the related sugars sucrose and sorbitol (a sugar substitute). Symptoms that may appear include irritability, upset stomach, vomiting, sweating, and/or sleepiness. If unrecognized and untreated, children with HFI will fail to grow at a normal rate, may develop a yellowing of the skin and whites of the eyes (jaundice), and have enlargement of the liver and spleen (hepatosplenomegaly). Without treatment, HFI can eventually lead to serious liver disease, hypoglycemic shock, seizures, and kidney or liver failure. In extreme cases, it can be fatal. For this reason, early detection and treatment is critical.
Symptoms of HFI can vary from mild to severe. Individuals with HFI often show an aversion to sweets and fruit, and those with mild HFI may, therefore, be protected from some of the symptoms they would otherwise experience. In addition, those with a severe course of the disease may develop serious liver disease later in life, even with a careful diet.
How Common Is HFI?
The estimated prevalence of HFI is approximately 1 in 20,000 to 1 in 30,000 individuals worldwide. However, the condition may be more or less common among certain ethnic groups.
How Is HFI Treated?
Treatment for HFI involves strict control of diet, eliminating all foods or products (for example, medicines or vitamins) containing fructose, sucrose, or sorbitol. With a carefully managed diet, individuals with HFI can be symptom-free, although symptoms will quickly return upon consuming fructose, sucrose, or sorbitol. In cases where liver disease has progressed to a life-threatening stage, liver transplantation is possible.
What Is the Prognosis for an Individual with HFI?
Without elimination of all fructose, sucrose, and sorbitol, HFI can be life threatening. Continued consumption of these sugars can lead to hypoglycemic shock, seizures, coma, serious liver disease, liver or kidney failure, and potentially death. With a careful diet, however, individuals with HFI may be symptom-free, have normal growth and development, and have a normal life expectancy. The earlier the condition is diagnosed and the diet adjusted, the less damage is done to the liver and kidneys and the better the overall prognosis. Early detection and diet modification are also important for age-appropriate growth. In a minority of individuals who have a severe form of HFI, liver disease may still develop, despite a careful diet.