Summary about Disease
Refsum disease is a rare, inherited metabolic disorder characterized by the body's inability to break down phytanic acid, a branched-chain fatty acid found in certain foods. This leads to an accumulation of phytanic acid in the blood and tissues, causing a variety of neurological and other health problems. It is an autosomal recessive condition.
Symptoms
The classic symptoms of Refsum disease include:
Retinitis Pigmentosa: A progressive eye disease that causes night blindness and loss of peripheral vision.
Anosmia: Loss of the sense of smell.
Sensorineural Hearing Loss: Hearing loss due to damage to the inner ear or auditory nerve.
Peripheral Neuropathy: Nerve damage causing weakness, numbness, and pain in the hands and feet.
Cerebellar Ataxia: Problems with coordination and balance.
Ichthyosis: Scaly, dry skin.
Cardiac Abnormalities: Including cardiomyopathy or arrhythmias.
Causes
Refsum disease is caused by mutations in the PHYH gene (formerly known as *PAHX*) that provides instructions for making the phytanoyl-CoA hydroxylase enzyme. This enzyme is essential for the alpha-oxidation of phytanic acid, the first step in its breakdown. Mutations in *PEX7* have also been shown to cause Refsum disease. Inheriting two mutated genes (one from each parent) is necessary to develop the disease (autosomal recessive inheritance). This impaired function leads to the accumulation of phytanic acid in the body.
Medicine Used
There is no specific "medicine" that cures Refsum disease. The primary treatment focuses on managing symptoms and reducing phytanic acid levels through diet.
Dietary Restriction: The cornerstone of treatment is a diet low in phytanic acid. This involves avoiding foods rich in phytanic acid, such as dairy products, beef, lamb, and certain green vegetables.
Plasmapheresis: In some cases, plasmapheresis (a procedure that removes phytanic acid from the blood) may be used to rapidly lower phytanic acid levels, especially during acute exacerbations.
Supportive therapies may be prescribed to manage specific symptoms, such as pain relievers for neuropathy or medications for cardiac problems.
Is Communicable
No, Refsum disease is not communicable. It is a genetic disorder and cannot be transmitted from person to person.
Precautions
The primary precaution for individuals with Refsum disease is strict adherence to a low-phytanic acid diet. Regular monitoring of phytanic acid levels in the blood is also important. Genetic counseling is recommended for families with a history of Refsum disease.
How long does an outbreak last?
Refsum disease is not characterized by "outbreaks." It is a chronic condition where symptoms progressively worsen over time if phytanic acid levels are not controlled. Acute exacerbations of symptoms can occur when phytanic acid levels become excessively high. However, these aren't outbreaks, they are worsening of the underlying chronic condition.
How is it diagnosed?
Refsum disease is diagnosed based on a combination of:
Clinical Evaluation: Assessment of symptoms such as retinitis pigmentosa, anosmia, peripheral neuropathy, and ataxia.
Blood Test: Elevated levels of phytanic acid in the blood are a key diagnostic marker.
Genetic Testing: Confirmation of mutations in the PHYH or *PEX7* gene.
Nerve Conduction Studies: To assess peripheral nerve function.
Electroretinogram (ERG): To evaluate retinal function.
Timeline of Symptoms
The onset and progression of symptoms can vary. Symptoms typically begin in childhood or adolescence, but can sometimes manifest later in life.
Early stages: Night blindness (retinitis pigmentosa) and loss of smell (anosmia) may be the first noticeable symptoms.
Progression: Peripheral neuropathy, ataxia, and hearing loss typically develop later.
Long-term: Cardiac problems and ichthyosis can also occur as the disease progresses. The rate of progression varies between individuals.
Important Considerations
Early diagnosis and treatment are crucial to slow the progression of Refsum disease and prevent long-term complications.
Lifelong adherence to a low-phytanic acid diet is essential.
Regular monitoring by a physician with experience in managing metabolic disorders is necessary.
Genetic counseling is recommended for families at risk.
Nutritional guidance from a registered dietician specializing in metabolic disorders is vital to ensure adequate nutrition while adhering to dietary restrictions.