How common is Refsum disease?

How common is Refsum disease?

About 60 cases of Refsum disease (RD) have been reported worldwide. Prevalence rates are not known but the disorder may be underdiagnosed. Prevalence has been estimated to be 1/1,000,000 in the United Kingdom. Males and females are affected equally.

What is the defect in Refsum disease?

Refsum disease is an inherited condition that causes vision loss, absence of the sense of smell (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.

Who discovered Refsum?

Refsum disease was first recognized as a distinct disease entity by Sigvald Refsum in the 1940s. The discovery of markedly elevated levels of the branched-chain fatty acid phytanic acid in certain patients marked Refsum disease as a disorder of lipid metabolism.

What is infantile Refsum disease?

Definition. Infantile Refsum disease (IRD) is a medical condition within the Zellweger spectrum of perixisome biogenesis disorders (PBDs), inherited genetic disorders that damage the white matter of the brain and affect motor movements. PBDs are part of a larger group of disorders called the leukodystrophies.

Is Refsum disease genetic?

Refsum disease is an autosomal recessive genetic disorder. Recessive genetic disorders occur when an individual inherits a non-working gene from each parent.

Is Refsum disease fatal?

Although it is rare, if phytanic acid levels become very high in people with Refsum disease, then a cardiac arrhythmia (irregular heartbeat) can occur which could be life threatening.

What causes Refsum disease?

Refsum disease is caused by a change (mutation) in the gene that makes an enzyme responsible for breaking down phytanic acid, a particular type of fatty acid which is derived by bacterial fermentation of green plants or algae.

How old do you have to be to have Refsum disease?

The age of onset of Refsum disease varies greatly. It may occur at any time from early childhood until around 50 years of age, but in most symptoms will have appeared by age 20. Males and females are affected in equal numbers.

How is the diagnosis of Refsum disease made?

The diagnosis of Refsum disease is suspected on the basis of clinical findings and a plasma phytanic acid concentration greater than 200 µmol/L in most affected individuals.

What kind of mutation causes adult Refsum disease?

Adult Refsum disease results from mutations in either the gene that encodes phytanoyl-CoA hydroxylase (PHYH) or PEX7, which impacts importation into the peroxisome. The PHYH gene spans 21.5 kb on chromosome 10p13 of the human genome and encodes an mRNA of about 1.6 kb.

What happens to hands and feet with Refsum disease?

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).

What do you need to know about Refsum disease?

Order NINDS Publications. Definition. Adult Refsum disease (ARD) is a rare genetic disease that causes weakness or numbness of the hands and feet (peripheral neuropathy). Due to a genetic abnormality, people with ARD disease lack the enzyme in peroxisomes that break down phytanic acid, a type of fat found in certain foods.

What causes vision loss in people with Refsum disease?

The vision loss associated with Refsum disease is caused by an eye disorder called retinitis pigmentosa. This disorder affects the retina, the light-sensitive layer at the back of the eye. Vision loss occurs as the light-sensing cells of the retina gradually deteriorate.

What’s the difference between infantile and adult Refsum disease?

Adult Refsum disease should not be confused with infantile Refsum disease, a peroxisome biogenesis disorder resulting from deficiencies in the catabolism of very long chain fatty acids and branched chain fatty acids (such as phytanic acid) and plasmalogen biosynthesis.

What are the mutations in the Refsum gene?

Refsum disease can result from mutations in the PHYH gene or the PEX7 gene and is inherited in an autosomal recessive pattern. [1] This table lists symptoms that people with this disease may have.