Information on the following diseases can be found in the Related Disorders section of this report:

• Acanthocytosis
• Tay Sach's Disease
• Gaucher's Disease
• Niemann-Pick Disease

Symptoms of Refsum disease may include vision impairment, degenerative nerve disease, failure of muscle coordination, and bone and skin changes. Symptoms may include night blindness, loss of peripheral vision, and numbness and weakness associated with failure of muscle coordination.

Affected individuals may experience an unusual burning or prickling sensation (paresthesia) of arms and legs. Neurological symptoms include unsteady walking with frequent falls (ataxia), and peripheral neuropathy (characterized by sensory, motor, and reflex changes). Skin changes may include dryness, itchiness, and scaliness.

An infantile form of Refsum disease exists that usually becomes apparent during the first year of life. In addition to early onset, it is characterized by developmental delay, vision and hearing impairment, enlargement of the liver and defective metabolism of bile acid.

Refsum disease is inherited as a recessive trait. The genes responsible for the failure in the metabolism of phytanic acid have been traced to the short arm of chromosome 10 (10pter-p11.2) and the long arm of chromosome 6 (6q22-q24).

Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered. For example, "chromosome 6q22" refers to band 22 on the long arm of chromosome 6. The notation "10pter" refers to the end or terminus of the short arm of chromosome 10. The numbered bands specify the location of the thousands of genes that are present on each chromosome.

Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.

Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.

All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

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.

There are many disorders caused by abnormal lipid metabolism. Acanthocytosis, also known as Lipoprotein Deficiency, is inherited as a recessive trait, and tends to occur more than once in families where it is found. This rare disorder usually begins in the first year of life and is marked by malnutrition, growth retardation, abdominal distention, and progressive neurological dysfunction. Curvature of the spine, muscle coordination impairment (ataxia), and eye problems including pigmentary retinal degeneration beginning at about ten years of age may also be symptomatic of Acanthocytosis.

Gaucher's Disease is an inherited disease of lipid metabolism caused by the failure to produce the enzyme glucocerebrosidase. It is the most common of the fourteen known lipid storage disorders which includes Tay-Sachs Disease, Fabry's Disease, and Niemann-Pick Disease. There are three types of Gaucher's Disease - Type I, II, and III. All three are characterized by the presence of Gaucher (lipid-laden) cells in the bone marrow and other organs such as the spleen and liver.

Tay-Sachs Disease is an infantile form of Ceroid-Lipofuscinosis. Tay- Sachs is a genetic disorder that causes the progressive destruction of the central nervous system. It is generally found among children of Eastern European Jewish heritage and becomes clinically apparent at about six months of age.

Niemann-Pick Disease is a rare, familial disorder of lipid metabolism characterized by the accumulation of sphingomyelin and cholesterol in the reticuloendothelial cells. There are at least five different forms of this type of lipidosis.

(For more information on these disorders, choose "Gaucher," "Tay-Sach," "Fabry," "Niemann," and "Acanthocytosis" as your search terms in the Rare Disease Database.)

Diagnosis
The presence of phytanic acid in blood or urine samples is diagnostic.

Treatment
Treatment of Refsum disease involves following a strict diet low in phytanic acid (found in dairy products, beef, lamb and some seafoods) and high in calories. The removal and reinfusion of blood plasma (plasmapheresis) may also be required. Other treatment is symptomatic and supportive.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com


High doses of vitamin A are thought by some researchers to retard the rate of degradation of eyesight in retinitis pigmentosa associated with classical (adult-onset) Refsum disease.

McKusick VA, ed. Online Mendelian Inheritance In Man (OMIM). The Johns Hopkins University. Refsum Disease. Entry Number; 266500: Last Edit Date; 3/4/2003.

TEXTBOOKS
Burns RS. Ataxia, Refsum Disease. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:604-05.

Beers MH, Berkow R, eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:215-16.

Steinberg D. Refsum Disease. In: Scriver CR, Beaudet AL, Sly WS, et al. Eds. The Metabolic Molecular Basis of Inherited Disease. 7th ed. McGraw-Hill Companies. New York, NY; 1995.

REVIEW ARTICLES
Pareyson D. Diagnosis of hereditary neuropathies in adult patients. J Neurol. 2003;250:148-60.

Bouillot S, Martin-Negrier Vital A, et al. Peripheral neuropathy associated with mitochondrial disorders: 8 cases and review of the literature. J Periph Nerv Syst. 2002;7:213-20.

Wierzbicki AS, Lloyd MD, Schofield CJ, et al. Refsum's disease: a peroxisomal disorder affecting phytanic acid alpha-oxidation. J Neurochem. 2002;80:727-35.

Wanders RJ, Jansen GA, Skjeldal OH. Refsum disease, peroxisomes, and phytanic acid oxidation: a review. J Neuropathol Exp Neurol. 2001;60:1021-31.

Wills AJ, Manning NJ, Reilly MM. Refsum's disease. QJM. 2001;94:403-06.

Grant CA, Berson EL. Treatable forms of retinitis pigmentosa associated with systemic neurological disorders. Int Ophthalmol Clin. 2001;41:103-10.

McGuinness MC, Wei H, Smith KD. Therapeutic developments in peroxisome biogenesis disorders. Expert Opin Exp Drugs. 2000;9:1985-92.

Moser HW. Molecular Genetics of peroxisomal disorders. Front Biosci. 2000;5:D298-306.

JOURNAL ARTICLES
Van den Brink DM, Brites P, Haasjes J, et al. Identification of PEX7 as the second gene involved in Refsum disease. Am J Hum Genet. 2003;72:471-77.

Gootjes J, Mooijer PA, Dekker C, et al. Biochemical markers predicting survival in peroxisome biogenesis disorders. Neurology. 2002;59:1746-49.

Barth PG, Gootjes J, Bode H, et al. Late onset white matter disease in peroxisome biogenesis disorder. Neurology. 2001;57:1949-55.

Oysu C, Aslan I, Basaran B, et al. The site of hearing loss in Refsum's disease. Int J Pediatr Otorhinolaryngol. 2001;61:129-34.

Walter C, Gootjes J, Mooijer PA, et al. Disorders of peroxisome biogenesis due to mutations in PEX1: phenotypes and PEX1 protein levels. Am J Hum Genet. 2001;69:35-48.

Korman SH, Mandel H, Gutman A. Characteristic urine organic acid profile in peroxisome biogenesis disorders. J Inherit Metab Dis. 2000;23:425-28.


Jansen GA, Hogenhout EM, Ferdinandusse S, et al. Human phytanoyl-CoA hydroxylase: resolution of gene structure and the molecular basis of Refsum's disease. Hum Mol Genet. 2000;9:1195-200.

Jansen GA, Ferdinandusse S, Hogenhout EM, et al. Phytanoyl-CoA hydroxylase deficiency. Enzymological and molecular basis of classical Refsum disease. Adv Edp Med. 1999;466:371-76.

FROM THE INTERNET
NINDS Refsum Disease Information Page. Reviewed 07-01-2001. 2pp.
www.ninds.nih.gov/health_and_medical/disorders/refsum_doc.htm

Refsum Disease. Genes and disease. nd. 2pp.
www.ncbi.nlm.nih.gov/books

Refsum Disease. nd. 2pp.
www.peroxisome.org/Scientist/Biochemistry/disorders/refsumtext.html

A Clinical Description of Refsum Syndrome
Refsum's Disease
www.srpf.a.se/forsk/refsum.html

Refsum Disease. Article Created: 1999-03-20. 1p.
http://healthlink.mcw.edu/article/921960794.html

Disease of Refsum. Rev 12-01-2003. 7pp.
www.snof.org/maladies/refsum.html

Refusm Disease. United Leukodystrophy Foundation. nd. 21pp.
www.ulf.org/ulf/intro/index.htm