Barth syndrome

BACKGROUND

Barth syndrome is a rare metabolic and neuromuscular disorder that appears to only affect males. At birth or a few months after birth, infants typically have reduced muscle tone and an enlarged heart that does not pump efficiently. Other characteristics of Barth syndrome include muscle weakness, fatigue, short stature, and frequent infections (caused by a weakened immune system).

Researchers estimate that Barth syndrome affects at least 50 families worldwide, but some experts believe that Barth syndrome is under-diagnosed. Quality studies determining the prevalence of the disorder are lacking. However, it is estimated that fewer than 10 babies are born with Barth syndrome each year in the United States. This suggests an incidence rate of one out of 300,000-400,000 births. On average, 50% of children born to a carrier mother will inherit the defective gene, but only boys will have symptoms. All daughters born to an affected male will be carriers.

There is currently no cure or specific treatment for Barth syndrome. Instead, treatment focuses on reducing the symptoms and preventing complications, such as infections. Severe infections and heart failure are common causes of death in affected children. Early diagnosis and treatment are essential for prolonged survival for boys born with Barth syndrome.

CAUSES

Mutated gene: Barth syndrome occurs when a person is born with a mutated, or abnormal, TAZ1 (or G4.5) gene. This abnormal gene is located on the X chromosome, which is a sex-determining chromosome. Males have one X and one Y chromosome, while females have two X chromosomes.

Inheritance: The mutated TAZ1 gene is passed down as an X-linked recessive trait. Since males have only one X chromosome, they will develop the disorder if they inherit just one copy of the mutated gene.

Females, on the other hand, would need to inherit two copies of the mutated gene (one in each of their two X chromosomes) in order to develop Barth syndrome. Although this could theoretically happen, there have been no reports of females who have Barth syndrome. Instead, females are typically carriers of Barth syndrome. This means that a female can have one copy of the mutated gene without experiencing symptoms of Barth syndrome.

Even though a mother who carries the mutated gene does not have the disorder, she can pass her mutated gene to each of her children. There is a 50% chance that a female carrier will pass her X chromosome to a son, and her son will develop the disorder. If the woman has a daughter, there is a 50% chance that the girl will be a carrier.

If a father has Barth syndrome, there is a 100% chance that each of his daughters will carry the mutated gene. Carriers can then pass their mutated genes to their children.

SIGNS AND SYMPTOMS

General: Most people with Barth syndrome experience all of the symptoms listed below. However, some people may have only a few of these abnormalities and, as a result, they are often misdiagnosed.

Cardiomyopathy: As infants, patients typically have cardiomyopathy, a condition that occurs when the heart is enlarged and unable to pump efficiently. Common symptoms of cardiomyopathy include difficulty breathing, poor appetite, irregular heartbeat, and slow weight gain.

Metabolism: The mitochondria, cellular structures which produce energy for cells, do not function properly in people with Barth syndrome. This is because a genetic mutation prevents the mitochondria from making enough of a lipid called tetralinoleoyl-cardiolipin. This is the main phospholipid of the mitochondrial inner membrane. Thus, patients with Barth syndrome typically have high levels of an organic acid, called 3-methylglutaconic acid, in their bodies.

Musculoskeletal: People born with Barth syndrome typically have delayed motor skills, reduced muscle tone (called hypotonia), and delayed growth, all of which may lead to varying degrees of physical disabilities.

Weakened immune system: People with Barth syndrome have weakened immune systems because they are born with abnormally low levels of white blood cells, called neutrophils. When there are not enough of these cells in the body, the condition is called neutropenia. Neutrophils make up 70% of all white blood cells in the body and are especially important in fighting off infections and diseases. Therefore, people with neutropenia have an increased risk of becoming sick.

Other: People with Barth syndrome typically experience chronic fatigue, low blood sugar levels (called hypoglycemia), diarrhea, and varying degrees of learning disabilities.

DIAGNOSIS

General: If Barth syndrome is suspected, medical tests, such as a urine analysis and complete blood count, may be performed. If these tests indicate Barth syndrome, a diagnosis can be confirmed with DNA testing. Other tests, such as an echocardiogram, may be performed to determine the severity of the condition.

Urine analysis: Most patients with Barth syndrome will have elevated levels of an organic acid, called 3-methylglutaconic acid, in their urine.

Complete blood count: A doctor may take a sample of the patient's blood to determine if he/she has low levels of neutrophils in his/her blood.

DNA test: A DNA test may be performed to confirm a diagnosis. A sample of the patient's blood is taken and analyzed in a laboratory for the presence of a mutated TAZ1 gene. If a mutation is present, a positive diagnosis is made.

If a female has a family history of Barth syndrome, a DNA test may be performed to determine if she carries a copy of the mutated TAZ1 gene. Although a carrier does not have Barth syndrome, she may pass a copy to her children.

Prenatal DNA testing: If a parent is a carrier of the mutated TAZ1 gene, prenatal testing may be performed at a hospital to determine if the fetus has the disorder. These types of tests are considered outpatient procedures. However, there are serious risks associated with prenatal tests, including miscarriage. Patients should discuss the potential health benefits and risks associated with these procedures before making any medical decisions.

During amniocentesis, a long, thin needle is inserted through the abdominal wall and into the uterus. A small amount of amniotic fluid is removed from the sac surrounding the fetus. The fluid is then analyzed for a mutated TAZ1 gene. This test is performed after 15 weeks of gestation. The risk of miscarriage ranges from one out of 200-400 patients. Some patients may experience minor complications, such as cramping, leaking fluid, or irritation where the needle was inserted.

During chorionic villus sampling (CVS), a small piece of tissue (chorionic villi) is removed from the placenta during early pregnancy. Depending on where the placenta is located, CVS can be performed through the cervix or through the abdomen. The tissue sample is then analyzed for a mutated TAZ1 gene. This procedure may be performed between the ninth and 14th week of gestation. The risks of infection or fetal damage are slightly higher than the risks of amniocentesis. Miscarriage occurs in about two percent of women who undergo this procedure.

Genetic counseling: Before and after genetic testing, it is recommended that people meet with genetic counselors. These professionals can help patients understand the risks of having a child with Barth syndrome. A genetic counselor can also explain the different types of genetic tests, including their potential risks and benefits. These counselors can also help patients understand the results and limitations of these tests.

Echocardiogram: An echocardiogram may also be performed to detect possible abnormalities in the heart muscle. This test is similar to an ultrasound that is used in pregnant women. A wand-like device (called a transducer) is rubbed on the patient's chest and sound waves produce images of the heart.

COMPLICATIONS

Blood clots: Cardiomyopathy makes patients more likely to develop blood clots. These blood clots may block blood vessels and block blood flow to important organs, including the brain, heart, and lungs. If blood flow to the heart is blocked, it may lead to a heart attack, and if blood flow to the brain is blocked, it may cause a stroke.

Cardiac arrest: Cardiomyopathy may cause irregular heartbeats. Sometimes the heart may beat too slowly to properly circulate blood throughout the body. Sometimes the heart beats too quickly to allow the heart to beat efficiently. Abnormal heartbeats may result in fainting. In serious cases, irregular heartbeats may cause the heart to suddenly stop beating (called cardiac arrest), and the patient is at risk of dying.

Heart failure: People with Barth syndrome typically have cardiomyopathy. Their hearts are enlarged and unable to pump as efficiently as healthy people. This increases the risk of experiencing heart failure, a degenerative condition that occurs when the heart is unable to beat efficiently and pump enough blood to meet the body's needs. Unlike cardiac arrest, which occurs when the heart suddenly stops working, heart failure is a long-term condition that generally worsens over time.

Severe infections: People with Barth syndrome have weakened immune systems because they have low levels of neutrophils in their blood. As a result, they have an increased risk of developing infections, which may be severe. If an infection enters the bloodstream, it may spread to vital organs and become a life-threatening condition.

TREATMENT

General: There is currently no cure or specific treatment for Barth syndrome. Instead, treatment focuses on reducing the symptoms and preventing complications, such as infections.

Physical therapy: Physical therapy may help patients improve their physical strength and motor coordination. Since babies with Barth syndrome usually have reduced muscle tone, a physical therapist may be able to help babies learn how to roll over, sit up, and walk. A variety of techniques, including exercises, stretches, traction, electrical stimulation, and massage, may be used during physical therapy sessions.

Antibiotics: Medications, called antibiotics, are used to treat bacterial infections, commonly associated with Barth syndrome. These medications kill the disease-causing bacteria. The exact type, dose, and duration of treatment depend on the type of infections, as well as the patient's age and overall health.

Side effects of antibiotics vary depending on the specific type of medication used. People should not stop taking antibiotics early, even if symptoms start to go away, because bacteria may still be present in the body. Stopping medication early may allow the infection to return and lead to antibiotic resistance. This is because the most resilient bacteria are the last to be killed. If medication is stopped, the bacteria may become resistance to treatment, and the medications will no longer be effective if taken in the future.

Granulocyte colony stimulating factor (GCSF): A medication, called granulocyte colony stimulating factor (G-CSF), has been used to help stimulate the production of neutrophils (which are also called granulocytes) in the bone marrow. As a result, this helps the body fight against infections.

Side effects are rare and may include bone pain, tenderness at the injection site, and high levels of lactate dehydrogenase and alkaline phosphatase in the blood.

Lifestyle: People with cardiomyopathy are encouraged not to smoke or gain excessive weight. They are also encouraged to eat a low-salt diet, participate in moderate exercise (30 minutes or more) on most days of the week, and limit or avoid alcohol consumption.

Heart medications: Patients with cardiomyopathy often require medications. Doctors may prescribe angiotensin-converting enzyme (ACE) inhibitors, such as enalapril (Vasotec©), lisinopril (Zestril© or Prinivil©), ramipril (Altace©), and captopril (Capoten©), to improve the heart's ability to pump blood. Side effects of ACE-inhibitors may include chronic, nonproductive cough (occurs in about 10% of patients), dizziness or weakness (caused by low blood pressure), increased potassium levels, skin rashes, and sudden swelling of the lips, face, and cheeks.

In addition, diuretics, such as furosemide (Lasix©), may help reduce fluid retention. Side effects of diuretics may include frequent urination and low potassium levels in the blood. Because of this, blood tests are performed periodically and a potassium supplement is prescribed if blood levels of potassium are low. Individuals may be asked to eat more fruits high in potassium, such as bananas and oranges, while on diuretic therapy.

Beta blockers, such as atenolol (Tenormin©), carvedilol (Coreg©), and metoprolol (Lopressor© or Toprol XL©), may improve the heart's function and reduce the risk of death. During the first several weeks of treatment, some patients experience worsening symptoms due to a decrease in oxygen circulation in the body. Other side effects may include low blood pressure, difficulty breathing, sexual dysfunction, nausea, and weakness with exertion.

Pacemaker: Some patients may benefit from pacemakers that regulate the contractions of the heart between the left and right ventricles. These pacemakers are surgically inserted into the heart. It is considered an inpatient procedure because patients typically stay in the hospital for one to three days after having a pacemaker implanted. The pacemaker is programmed to fit the patient's particular pacing needs. A return visit is scheduled to refine the settings. The battery-life of pacemakers is about 10 years. When the battery is low, the pacemaker is surgically replaced.

It is normal for the surgical wound to be somewhat painful and swollen for a few days after the procedure. This can usually be treated with medications, such as ultram (Tramadol©) or ibuprofen (Motrin©). The wound may also appear mildly red for a few days. However, if the area of redness enlarges, a doctor should be notified due to the potential for a serious infection. If there are no other problems, most individuals who have a permanent pacemaker surgically implanted can go home the next day. They can usually return to normal activities within six weeks. For several weeks after having a pacemaker implanted, the individual may be asked not to lift more than five pounds or raise the affected arm over his/her shoulder.

Heart transplant: Patients with serious cardiomyopathy may develop heart failure, which is fatal unless treated with a heart transplant. However, people often have to wait several months to years before a heart is available that matches the patient's. Sometimes a person can be supported with mechanical heart assistance devices, called ventricular assist devices (VADs) as they wait for a heart. If a person with heart failure is not a candidate for a heart transplant, a VAD may provide long-term support.

INTEGRATIVE THERAPIES

Note: Currently, there is a lack of scientific data on the use of integrative therapies for the treatment or prevention of Barth syndrome. However, some therapies have been studied as possible treatments for symptoms commonly associated with the disorder.

Good scientific evidence:

Coleus: The root extract of coleus is known as forskolin. Forskolin may improve cardiovascular function in patients with cardiomyopathy. However, additional study is needed to confirm these findings.

Coleus is generally regarded as safe, as very few reports have documented adverse effects. However, only a few short-term trials have assessed its safety in a small sample size of patients. Avoid if allergic to Coleus forskohlii or related species. Avoid with active bleeding. Use cautiously with a history of bleeding or hemostatic disorders, drug-related hemostatic problems, asthma, diabetes, thyroid disorders, or heart disease. Use cautiously if taking anticoagulant, anti-thrombotic, and/or antiplatelet medications. Stop taking coleus at least two weeks before and immediately after surgical, dental, or diagnostic procedures that have bleeding risks. Avoid if pregnant or breastfeeding.

Ginseng: A small number of studies report that ginseng may stimulate the immune cells in the body, improve the effectiveness of antibiotics in people with acute bronchitis, and enhance the body's response to flu vaccines.

Avoid if allergic to ginseng or plants in the Araliaceae family, such as English ivy. There has been a report of a serious life-threatening skin reaction, possibly caused by contaminants in ginseng formulations.

Zinc: Zinc products have been used since ancient Egyptian times to enhance wound healing. Zinc appears to be an essential element that the immune system needs to function properly. However, there is limited research available on the effect of zinc supplementation on immune function. Also, most research focuses on patients with specific diseases. Zinc gluconate appears to have beneficial effects on immune cells, improving CD3 and CD4 counts and increasing CD4/CD8 ratios in children. There are relatively few studies that examine zinc levels and the effects of zinc supplementation on the health of the elderly population. Further research is needed to determine if zinc supplementation can enhance immune function.

Zinc is generally considered safe when taken at the recommended dosages. Avoid a zinc product called zinc chloride because studies have not been done to evaluate its safety or effectiveness. While zinc appears safe during pregnancy in the recommended doses, caution should be used since studies cannot rule out the possibility of harm to the fetus.

Unclear or conflicting scientific evidence:

Astragalus: In traditional Chinese medicine (TCM), astragalus is commonly found in mixtures with other herbs. Astragalus has been suggested as an immune system stimulant in preliminary laboratory and animal research and in traditional accounts. Reliable human studies are lacking. High-quality human research is necessary before a firm conclusion can be drawn.

Avoid if allergic to astragalus, peas, or any related plants. Avoid with a history of Quillaja bark-induced asthma. Avoid if taking aspirin, aspirin products, or herbs and supplements with similar effects. Avoid with inflammation, fever, stroke, organ transplant, or autoimmune diseases (such as lupus). Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Use cautiously with bleeding disorders, diabetes, high blood pressure, lipid disorders, or kidney disorders. Use cautiously if taking blood-thinners, blood sugar regulating drugs, diuretics, or with herbs and supplements with similar effects. Avoid if pregnant or breastfeeding.

Beta-carotene: Beta-carotene is a member of the carotenoids, which are very colorful (red, orange, yellow), fat-soluble compounds. They are naturally found in many fruits, grains, oils, and vegetables (e.g. green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers). Preliminary research of beta-carotene for immune system maintenance or stimulation shows mixed results. Further research is needed before a conclusion can be drawn.

Avoid if sensitive to beta-carotene, vitamin A, or any other ingredient in beta-carotene products (e.g. gelatin).

Bovine colostrum: Bovine colostrum is the pre-milk fluid produced from cow breast glands during the first two to four days after birth. Bovine colostrum contains proteins called immunoglobulin antibodies that are involved in the immune response. It has been suggested that bovine colostrum may improve immune function. However, further research is needed before a firm conclusion can be made.

Avoid if allergic or hypersensitive to dairy products. Use bovine colostrum cautiously. Toxic compounds, such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and dichlordiphenyldichloroethylene (DDE) have been found in human colostrum and breast milk. Thus, it is possible that these substances may be found in bovine colostrum. Avoid with cancer or if at high-risk of cancer. Use cautiously with immune system disorders or atherosclerosis (hardening of the arteries). Use cautiously if taking medications, such as anti-diarrheal agents (e.g. Imodium©), insulin, or CNS agents (e.g. amphetamines, caffeine). Avoid if pregnant or breastfeeding.

Cat's claw: Cat's claw is widely used in the United States and Europe, and it is one of the top herbal remedies sold, despite a lack of high-quality human evidence. A few early studies suggest that cat's claw may boost the immune system. However, results from different studies have produced conflicting results. Therefore, there is not enough information to make a firm recommendation for this use.

Avoid if allergic to Cat's claw, Uncaria plants, or plants in the Rubiaceae family (e.g. gardenia, coffee, or quinine). Avoid with a history of immune disorders (e.g. AIDS, HIV, some types of cancer, multiple sclerosis, tuberculosis, rheumatoid arthritis, or lupus). Use cautiously with bleeding disorders or with a history of stroke. Use cautiously if taking drugs that may increase the risk of bleeding. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Avoid if pregnant or breastfeeding. Cat's claw may be contaminated with other Uncaria species, including Uncaria rhynchophylla (used in Chinese herbal preparations under the name Gou-Teng), which may cause low blood pressure, lower heart rate, or act as a neuroinhibitor. Reports exist of the potentially toxic Texan grown plant Acacia gregii being substituted for cat's claw.

Coenzyme Q10: Coenzyme Q10 (CoQ10) is produced by the human body and is necessary for basic functioning of cells. There is conflicting evidence from research on the use of CoQ10 in patients with dilated or hypertrophic cardiomyopathy. Better research is needed in this area before a recommendation can be made.

Allergies associated with Coenzyme Q10 supplements have currently not been reported; rash and itching have been reported rarely. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Use cautiously with a history of blood clots, diabetes, high blood pressure, heart attack, or stroke. Use cautiously if taking anticoagulants (blood thinners), antiplatelet drugs, or blood pressure, blood sugar, cholesterol, or thyroid regulating drugs. Avoid if pregnant or breastfeeding.

Copper: Copper is a mineral that occurs naturally in many foods, including vegetables, legumes, nuts, grains, fruits, shellfish, avocado, beef, and animal organs (e.g. liver and kidneys). Copper is involved in the development of immune cells and immune function in the body. Severe copper deficiency appears to have negative effects on immune function. However, further research is needed to fully understand copper's effects on the immune system.

Patients should talk to their healthcare providers before taking copper supplements. Avoid if allergic to copper. Avoid use of copper supplements when recovering from diarrhea. Avoid with hypercupremia. Avoid with HIV/AIDS, genetic disorders affecting copper metabolism (e.g. Wilson's disease), Indian childhood cirrhosis, or idiopathic copper toxicosis. Use water-containing copper concentrations greater than six milligrams per liter cautiously. Use cautiously with anemia, joint pains, muscle pains, or if at risk for selenium deficiency. The recommended dietary allowance (RDA) is 1,000 micrograms for pregnant women. The RDA for breastfeeding women is 1,300 micrograms.

Echinacea: Extracts of Echinacea species have attracted recent scientific interest because they may have immune stimulant properties. Echinacea has been studied alone and in combination with other herbs and supplements for immune system stimulation (including in patients receiving cancer chemotherapy). It remains unclear if this is an effective treatment. Additional studies are needed in this area before conclusions can be drawn regarding safety or effectiveness.

Avoid if allergic to plants in the Asteraceae or Compositae family (e.g. ragweed, chrysanthemums, marigolds, daisies). Avoid Echinacea injections. Avoid with a history of liver disease or if taking an antibiotic called amoxicillin. Avoid in organ transplant recipients. Use cautiously if driving or operating heavy machinery or with history of asthma, diabetes, immune disorders (e.g. lupus, tuberculosis, AIDS/HIV), or rheumatologic conditions (e.g. rheumatoid arthritis). Avoid if pregnant or breastfeeding. Tinctures may contain large amounts of alcohol.

Gamma linolenic acid (GLA): Gamma linolenic acid (GLA) is a dietary fatty acid that is found in many plant oil extracts. Commercial products are typically made from seed extracts from evening primrose (average oil content 7-14%), blackcurrant (15-20%), borage oil (20-27%), and fungal oil (25%). Few clinical trials have investigated the effect of GLA on immune responses in healthy human subjects. GLA, as blackcurrant seed oil, may offer some benefits. Further study is required before a definite conclusion can be made.

Use cautiously with drugs that increase the risk of bleeding, such as anticoagulants or anti-platelet drugs. Avoid if pregnant or breastfeeding.

Goldenseal: Goldenseal is one of the five top-selling herbal products in the United States. However, there is little scientific evidence about its safety or effectiveness. Goldenseal has sometimes been suggested as an immune system stimulant. However, there is little human or laboratory evidence available in this area. More research is needed before a firm conclusion can be drawn.

Avoid if allergic or hypersensitive to goldenseal or any of its constituents (e.g. berberine and hydrastine). Use cautiously with bleeding disorders, diabetes, or low blood sugar. Avoid if pregnant or breastfeeding.

Maitake: Maitake mushrooms (Grifola frondosa) are fungi that can be eaten. Animal and laboratory studies suggest that beta-glucan extracts from maitake may alter the immune system. However, reliable studies in humans are currently not available.

Maitake has not been studied thoroughly in humans, and its effects are not well known. Because it has been used historically as a food, it is thought that low doses may be safe. Avoid if allergic or hypersensitive to maitake. Use cautiously with a medical history of low blood pressure, diabetes, and with drugs, herbs, or supplements that treat such conditions. Avoid if pregnant or breastfeeding.

Massage: Preliminary evidence suggests that massage therapy may preserve immune function. Further research is needed before a firm conclusion can be made.

Avoid with bleeding disorders, low platelet counts, or if taking blood-thinning medications (e.g. heparin or warfarin). Areas should not be massaged where there are fractures, weakened bones from osteoporosis or cancer, open/healing skin wounds, skin infections, recent surgery, or blood clots. Use cautiously with a history of physical abuse or if pregnant or breastfeeding. Massage should not be used as a substitute for more proven therapies for medical conditions. Massage should not cause pain to the client.

Meditation: Various forms of meditation have been practiced for thousands of years throughout the world, with many techniques originating in Eastern religious practices. Preliminary research reports increased antibody response after meditation. Further study is needed to confirm these findings.

Use cautiously with underlying mental illnesses. People with psychiatric disorders should consult with their primary mental healthcare professionals before starting a program of meditation, and they should explore how meditation may or may not fit in with their current treatment plans. Avoid with a risk of seizures. The practice of meditation should not delay the time to diagnosis or to find treatment with more proven techniques or therapies, and it should not be used as the sole treatment approach to illnesses.

Mistletoe: Once considered a sacred herb in Celtic tradition, mistletoe has been used for centuries for high blood pressure, epilepsy, exhaustion, anxiety, arthritis, vertigo (dizziness), and degenerative inflammation of the joints. A few small trials found mistletoe to be promising as an immunostimulant in individuals with the common cold. Further study is needed to determine whether or not mistletoe can help boost the body's immune system.

Avoid if allergic or hypersensitive to mistletoe or to any of its constituents. Life-threatening allergic reactions, called anaphylactic reactions, have been described after injections of mistletoe. Avoid with acute highly febrile inflammatory disease, thyroid disorders, seizure disorders, or heart disease. Use cautiously with diabetes, glaucoma, or if taking drugs called cholinergics, which treat nervous system disorders.

Probiotics: Probiotics are beneficial bacteria and are sometimes called friendly germs. They help maintain a healthy intestine and aid in digestion. Most probiotics come from food sources, especially cultured milk products. Probiotics can be taken as capsules, tablets, beverages, powders, yogurts, and other foods. A type of probiotic, called Lactobacillus, which is found in fermented milk, low-fat milk, and lactose-hydrolyzed low-fat milk, may enhance immune function. Another probiotic, called Bifidobacterium, has been studied in the elderly and it may have similar effects. However, commercially produced yogurt may not yield similar benefits. There is some evidence that probiotics added during food preparation (e.g., waffles with Enterococcus faecium M-74 added) can enhance immune functioning. More studies are needed, particularly with yogurt, before a firm conclusion can be made.

Probiotics are generally considered safe and side effects are reported to be uncommon. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.

Shiitake: Shiitake mushrooms were originally grown on natural oak logs found in Japan. Today, they are sold throughout the United States. These mushrooms are large, black-brown in color, and have an earthy rich flavor. Early research suggests that shiitake may enhance the immune response. However, further research is needed to confirm these findings.

Avoid if allergic or hypersensitive to shiitake mushrooms. Avoid if pregnant or breastfeeding.

Thymus extract: Thymus extracts for nutritional supplements are usually derived from young calves (bovine source). Preliminary evidence suggests that thymus extract may increase left ventricular function, exercise tolerance, and survival. Additional study is needed to determine if thymus extract is an effective treatment for cardiomyopathy.

Avoid if allergic or hypersensitive to thymus extracts. Use bovine thymus extract supplements cautiously due to potential for exposure to the virus that causes "mad cow disease." Avoid use with an organ transplant or with other forms of allografts or xenografts. Avoid with thymic tumors, myasthenia gravis (a neuromuscular disorder), or untreated hypothyroidism. Avoid if taking immunosuppressants or hormonal therapy. Avoid if pregnant or breastfeeding. Thymic extract increases the ability of a male's sperm to move and swim towards a female's egg.

Vitamin A: Vitamin A is a fat-soluble vitamin, which is derived from two sources: retinoids and carotenoids. Retinoids (e.g. retinal and retinoic acid) are found in animal sources, including the liver, kidney, eggs, and dairy products. Carotenoids (e.g. beta-carotene) are found in plants, including dark or yellow vegetables and carrots. Vitamin A deficiency may weaken the immune system, but there is no clear evidence that additional vitamin A supplementation is beneficial for immune function in patients who are not vitamin A deficient.

Avoid if allergic or hypersensitive to vitamin A. Vitamin A toxicity can occur if taken at high dosages. Use cautiously with liver disease or alcoholism. Smokers who consume alcohol and beta-carotene may have an increased risk for lung cancer or heart disease. Vitamin A appears safe in pregnant women if taken at recommended doses. Use cautiously if breastfeeding because the benefits or dangers to nursing infants are not clearly established.

Vitamin B6: Major sources of vitamin B6 include cereal grains, legumes (beans), vegetables (e.g. carrots, spinach, peas), potatoes, milk, cheese, eggs, fish, liver, meat, and flour. Vitamin B6 is important for immune system function in older individuals. One study found that the amount of vitamin B6 required to reverse weakened immune systems in elderly people was more than the current recommended dietary allowance (RDA). Well-designed clinical trials on vitamin B6 supplementation for this indication are needed before a recommendation can be made.

Some individuals seem to be particularly sensitive to vitamin B6 and may have problems at lower doses. Vitamin B6 is likely safe when taken by mouth in doses that do not exceed the Recommended Dietary Allowance (RDA). Avoid excessive dosing. The RDA for pregnant women is 1.9 milligrams per day. There is some concern that high-dose pyridoxine taken by a pregnant mother can cause seizures in a newborn. The RDA in breastfeeding women is 2 milligrams per day.

Vitamin E: Studies of the effects of vitamin E supplementation on immune system function have yielded mixed results. Further research is needed before a clear conclusion can be drawn.

Avoid if allergic or hypersensitive to vitamin E. For short periods of time, vitamin E supplementation is generally considered safe in the recommended doses.

Fair negative scientific evidence:

DHEA: DHEA (dehydroepiandrosterone) is a hormone produced by the adrenal glands in the body. Although authors of some textbooks and review articles have suggested that DHEA may stimulate the immune system, current scientific evidence does not support this claim.

Avoid if allergic to DHEA. Avoid with a history of seizures. Use cautiously with adrenal or thyroid disorders. Use cautiously if taking anticoagulants or drugs, herbs, or supplements for diabetes, heart disease, seizures, or stroke. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Avoid if pregnant or breastfeeding.

Lycopene: Lycopene is a carotenoid found in tomatoes, and it is present in human serum, liver, adrenal glands, lungs, prostate, colon, and the skin. It has been proposed that lycopene and other carotenoids, such as beta-carotene, may stimulate the immune system. However, several studies of lycopene supplements and tomato juice intake in humans report no effects on the immune system.

Avoid if allergic to tomatoes or to lycopene. Due to a lack of conclusive data, avoid if pregnant or breastfeeding.

PREVENTION

There is currently no known method of prevention for Barth syndrome.

If a female has a family history of Barth syndrome, genetic testing may be performed to determine if she carries the mutated gene. Although carriers do not have the disease, they can pass copies of their mutated gene to each of their children.

Prenatal DNA testing may be performed if there is a family history of Barth syndrome. However, there are health risks associated with prenatal testing, including miscarriage. Therefore, patients should discuss the potential health risks and benefits with their healthcare provider before making any health-related decisions.

Before and after genetic testing, it is recommended that people meet with genetic counselors. These professionals can help patients understand the risks of having a child with Barth syndrome. A genetic counselor can also explain the different types of genetic tests, including their potential risks, benefits, and limitations. These counselors can help patients understand the results and limitations of these tests.

People who are diagnosed with Barth syndrome can help reduce their risk of acquiring infections. For instance, people are encouraged to avoid close contact with individuals who have contagious illnesses. Practicing good hygiene and regularly washing the hands with soap and water may also help reduce the risk of acquiring infections. In addition, antibiotics should only be taken when prescribed. This helps reduce the risk of developing antibiotic-resistant bacterial infections in the future.

AUTHOR INFORMATION

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

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