Meyahealth
HomeGeneticsConditionRefsum disease
Back to Condition
Refsum disease
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Refsum disease

Refsum disease is a rare inherited disorder that causes vision loss, anosmia, and a spectrum of neurological and systemic symptoms. The condition results from mutations that impair the breakdown of phytanic acid, leading to its toxic accumulation.

Description

Refsum disease is an inherited condition that causes vision loss, absence of (anosmia), and a variety of other signs and symptoms.

The vision loss associated with Refsum disease is caused by an eye disorder called retinitis pigmentosa. This disorder affects , the light-sensitive layer at the back of the eye. Vision loss occurs as the light-sensing cells of the retina gradually deteriorate. The first sign of retinitis pigmentosa is usually a loss of night vision, which often becomes apparent in childhood. Over a period of years, the disease disrupts side (peripheral) vision and may eventually lead to blindness.

Vision loss and anosmia are seen in almost everyone with Refsum disease, but other signs and symptoms vary. About one-third of affected individuals are born with bone abnormalities of the hands and feet. Features that appear later in life can include progressive muscle weakness and wasting; poor balance and coordination (ataxia); hearing loss; and dry, scaly skin (ichthyosis). Additionally, some people with Refsum disease develop an abnormal heart rhythm (arrhythmia) and related heart problems that can be life-threatening.

Frequency

The prevalence of Refsum disease is unknown, although the condition is thought to be uncommon.

Causes

More than 90 percent of all cases of Refsum disease result from mutations in the PHYH gene. The remaining cases are caused by mutations in a gene called PEX7.

The signs and symptoms of Refsum disease result from the abnormal buildup of a type of fatty acid called phytanic acid. This substance is obtained from the diet, particularly from beef and dairy products. It is normally broken down through a process called alpha-oxidation, which occurs in cell structures called . These sac-like compartments contain enzymes that process many different substances, such as fatty acids and certain toxic compounds.

Mutations in either the PHYH or PEX

Frequently Asked Questions

Because Refsum disease can cause life‑threatening arrhythmias, an annual ECG and Holter monitor are recommended, with more frequent checks if you develop palpitations, dizziness, fainting, or unexplained shortness of breath. If you experience sudden chest pain, severe palpitations, or loss of consciousness, seek emergency care immediately.
strict low‑phytanic‑acid diet can stabilize or modestly improve visual function in many patients, especially if started early, but it does not reverse existing retinal damage. Low‑vision aids, retinal prosthesis trials, and vitamin A supplementation (under ophthalmologist supervision) are the main supportive options. Regular ophthalmologic exams every 6–12 months are essential to monitor progression.
Phytanic acid comes from the fat in ruminant meat (beef, lamb, pork), dairy products (whole milk, cheese, butter), and certain fish (e.g., cod liver oil). A low‑phytanic‑acid diet eliminates these items and replaces them with plant‑based oils, low‑fat dairy alternatives, and lean poultry. Regular blood tests every 3–6 months help confirm that levels stay within the target range (usually < 50 µmol/L).
Testing for pathogenic variants in the PHYH and PEX7 genes confirms the diagnosis. Once the specific mutation is known, carrier testing can be offered to siblings and extended family. For future pregnancies, options include pre‑implantation genetic diagnosis (PGD) with IVF, prenatal chorionic villus sampling, or amniocentesis to determine if the fetus carries the same mutation.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ