Heredopathia Atactica Polyneuritiformis
Adult Refsum disease (ARD) is one of a group of genetic diseases called leukodystrophies , which damage the white matter of the brain and affect motor movements. Due to a genetic abnormality, people with ARD disease lack the enzyme that breaks down phytanic acid, a substance commonly found in foods. As a result, toxic levels of phytanic acid build up in the brain, blood, and other tissues. The disease usually begins in late childhood with increasing night blindness due to degeneration of the retina (retinitis pigmentosa) and loss of the sense of smell (anosmia). If the disease progresses, other symptoms may include deafness, problems with balance and coordination (ataxia), weakness or numbness (peripheral neuropathy), dry and scaly skin (ichthyosis), and heartbeat abnormalities (cardiac arrhythmias). Some individuals will have shortened bones in their fingers or toes, or a visibly shortened fourth toe. Although the disease usually appears in early childhood, some people will not develop symptoms until their 40s or 50s.
The primary treatment for ARD is to restrict or avoid foods that contain phytanic acid, including dairy products; beef and lamb; and fatty fish such as tuna, cod, and haddock. Some individuals may also require plasma exchange (plasmapheresis) in which blood is drawn, filtered, and reinfused back into the body, to control the buildup of phytanic acid.
ARD is the most treatable of the leukodystrophies because phytanic acid is not produced by the body, but is only found in foods. With treatment, muscle weakness, numbness, and dry and scaly skin generally disappear. However, vision and hearing problems may persist and the sense of smell may not return. Untreated, ARD can lead to death caused by heartbeat abnormalities.
Prepared by the National Institutes of Health