carnitine palmitoyltransferase II deficiency
What is Carnitine Palmitoyltransferase II Deficiency?
Carnitine palmitoyltransferase II deficiency (CPT II deficiency) is an inherited disease in which the body cannot process long-chain fatty acids and turn them into energy. This is due to a defective enzyme.
There are three versions of the disease, listed below, each with a very different profile.
Lethal Neonatal Form
The lethal neonatal form of CPT II deficiency is the most severe form of the disease. Symptoms begin within days of birth and include liver failure, respiratory failure, a weakened and/or inflamed heart, irregular heartbeat leading to heart attack, kidney disease, and brain abnormalities. Usually these infants die within the first year of life.
Severe Infantile Hepatocardiomuscular Form
Symptoms of the severe infantile hepatocardiomuscular form of CPT II deficiency usually begin between 6 months and 2 years of age. They include liver failure, a weakened and/or inflamed heart, seizures, low blood sugar, abdominal pain, headache, muscle weakness in the arms and legs, and irregular heartbeat which can result in sudden death during infancy. Severe episodes are often triggered by fasting, infection, or fever.
The myopathic form of CPT II deficiency is the most common and least severe form of the disease. Symptoms can begin at any time from childhood to one’s 60s. People with the myopathic form of CPT II deficiency experience periodic attacks involving their muscles. These episodes are characterized by muscle pain and weakness. In many people with the disease, muscle tissue breaks down during these periods, causing brown or red-colored urine. Rarely, this can cause kidney problems. These attacks can be brought on by exercise, exposure to cold, stress, general anesthesia, sleep deprivation, or long periods of time without eating. Between attacks, people with the myopathic form of CPT II deficiency are typically normal.
The episodes of muscle pain are usually mild. Some people experience a limited number of severe attacks with long periods of normalcy. A smaller number of people experience frequent muscle pain that impairs their normal activity.
Most commonly, carriers of CPT II deficiency do not have any symptoms of the disease, however a small number of symptomatic carriers have been reported.
The myopathic form of CPT II deficiency is more often seen in men than women. Studies have shown the ratio of symptomatic men to women to be as high as 5-to-1. The reason for this gender differential is not well understood.
How common is Carnitine Palmitoyltransferase II Deficiency?
CPT II deficiency is rare. The lethal neonatal form has been documented in 13 families, while the severe infantile hepatocardiomuscular form has been studied in 20 families. There are more than 200 known cases of the myopathic form, however scientists believe this form often goes unrecognized, particularly in its mildest cases, and may be more common than studies have indicated.
How is Carnitine Palmitoyltransferase II Deficiency treated?
There is no cure for CPT II deficiency, and very little can be done to help infants and children with the more severe forms of the disease, other than to treat symptoms as they arise.
For people with the myopathic form, there are recommendations that can help prevent attacks. Frequent meals with a high-carbohydrate, low-fat diet can be helpful. Supplements of carnitine may also be recommended. During infection, a physician may recommend infusions of glucose. Circumstances to avoid include strenuous exercise, long periods of time without eating, and extreme cold.
During attacks, a person with the myopathic form of CPT II deficiency should drink plenty of fluids to avoid kidney problems.
People with the myopathic form of CPT II deficiency should avoid taking ibuprofen, valproic acid, and diazepam in high doses. They should also notify their physician before undergoing general anesthesia, as this can provoke an episode of muscle pain and weakness.
What is the prognosis for a person with Carnitine Palmitoyltransferase II Deficiency?
Infants with the lethal neonatal form of CPT II deficiency typically die within the first year of life. Infants and children with the severe infantile hepatocardiomuscular form are susceptible to life-threatening heart problems and typically have shortened lifespans with numerous medical problems.
People with the myopathic form of the disease typically live normal lifespans with periodic muscle problems. This form of the disease is usually manageable and allows for a good quality of life.