Refsum

Refsum disease is an extremely rare and complex disorder that affects many parts of the body.  A form of the retinal degenerative disease known as retinitis pigmentosa (RP) is a common feature of this disease.

What is Refsum Disease?

Refsum disease is an extremely rare and complex disorder that affects many parts of the body.  A form of the retinal degenerative disease known as retinitis pigmentosa (RP) is a common feature of this disease.

What are the symptoms?

Individuals with Refsum disease are unable to metabolize phytanic acid.  As a result, high levels of phytanic acid accumulate in the blood and tissue.  It is thought that disorders associated with this disease result from harmful levels of phytanic acid.  Phytanic acid is found in meat, fish, and dairy products.  The body also converts phytol, a substance found in green leafy vegetables, to phytanic acid.

Refsum disease is usually diagnosed during childhood or young adulthood when vision problems due to RP become apparent. Progressive vision loss from RP begins when harmful levels of phytanic acid collect beneath the retina.  The retina is essential to vision as it converts light into electrical impulses and then transfers these impulses to the brain via the optic nerve.

The first symptom of RP is night blindness followed by a gradual loss of peripheral (side) vision.  Night blindness makes vision difficult in dark or dimly lit places.  The loss of peripheral vision is often referred to as tunnel vision.  RP tends to progress slowly in patients with Refsum disease.

Cataracts, which are common to RP, are also seen in individuals with Refsum disease.  Cataracts hamper vision by clouding the lens of the eye making it difficult for light to reach the retina.  In most cases, however, cataracts can be surgically removed.  The extent of vision loss with Refsum disease varies greatly depending on the levels of phytanic acid and the presence of cataracts.

In addition to vision-related disorders, individuals with Refsum disease experience other sensory complications.  Loss of smell (anosmia) usually occurs in early childhood but may go undiagnosed until other more pronounced symptoms become apparent.  Gradual or sudden hearing loss can occur in adulthood, usually after the third decade.

Cardiac (heart) abnormalities, peripheral neuropathy (nerve disorder causing loss of sensation), ataxia (balance disorder), paresthesia (unusual burning or prickling sensation of skin), ichthyosis (dry, scaly skin), anorexia (loss of appetite), and skeletal bone abnormalities are also common.

Is it an inherited disease?

Refsum disease is genetically passed through families by the  autosomal recessive pattern of inheritance.  In this type of inheritance, both parents, called carriers, have one gene for the disease paired with one normal gene.  Each of their children then has a 25 percent chance (or 1 chance in 4) of inheriting the two  Refsum disease genes (one from each parent) needed to cause the disorder.  Carriers are unaffected because they have only one copy of the gene.   At this time, it is difficult to determine who is a carrier for Refsum disease until after the birth of an affected child.  However, slightly elevated levels of phytanic acid have been detected in some people thought to be carriers for Refsum disease.

What treatment is available?

A diet low in foods containing phytanic acid and phytol may arrest the progression of RP and lessen the severity of other complications associated with Refsum disease. To help control these complications, it is important that patients maintain their body weight.  Weight loss releases phytanic acid stored in body tissue and increases symptoms associated with the disease. Patients should be supervised by a physician to monitor blood levels of phytanic acid and adjust dietary regimens.  A physician can also prescribe medications to enhance appetite.

Individuals with Refsum disease should have their heart monitored regularly by a physician.  A neurologist can evaluate and monitor individuals with peripheral neuropathy and ataxia.  Lotions may help control skin problems.  As vision declines, individuals with Refsum disease may benefit from the use of low-vision aids, including electronic, computer-based, and optical aids.  Orientation and mobility training, adaptive skills, job placement, and income assistance are available through community resources.  Ongoing scientific research is directed at identifying the gene that causes Refsum disease to develop improved treatments.

Researchers have identified genetic variations that cause Refsum disease. These genetic findings are giving scientists targets for treatment development.

Are there any other related diseases or syndromes?

Refsum disease can be confused with other similar disorders.  Bassen-Kornzweig disease, also known as abetalipoproteinemia, is characterized by retinal degeneration, neuromuscular disability and dietary fat intolerance.  Kearns-Sayre syndrome involves retinal degeneration, ptosis (drooping of upper eyelid), deafness, muscular dystrophy, and cardiac abnormalities.  Expert medical consultation can distinguish between these disorders.