Refsum disease is a genetic condition caused by an enzyme in our cells, called the peroxisome, not breaking down a substance called phytanic acid. This leads to a buildup of this substance in the body.
The main symptom is vision loss known as retinitis pigmentosa (RP), causing issues like night blindness and tunnel vision, eventually leading to blindness. People with Refsum disease may experience various symptoms such as deafness, loss of the sense of smell (anosmia), lack of muscle control (ataxia), nerve degeneration leading to weakness or pain, dry scaly skin (ichthyosis), shortness of certain bones in the hands and feet, and heart rhythm problems. Not everyone has all these symptoms, and they can vary between individuals, even in the same family. Symptoms can start at different ages, ranging from age 2 to as late as the 40s or 50s, although most people have symptoms before turning 20. Currently, there’s no cure for the main cause of this condition. Treatment involves avoiding foods high in phytanic acid, like dairy products, beef, and certain seafood. While some symptoms may get better with treatment, it’s unclear if it helps with RP, deafness, or anosmia. In some cases, removing and replacing blood plasma may be necessary to lower phytanic acid levels in the blood.
Refsum disease is caused by pathogenic (disease-causing) variants in multiple genes and the test we offer covers the PHYH gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
Other names for this condition are hereditary motor and sensory neuropathy type IV, heredopathia atactica polyneuritiformis, and phytanic acid storage disease.