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Study of Dietary N-3 Fatty Acids in Patients With Retinitis Pigmentosa and Usher Syndrome

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00004345
Recruitment Status : Terminated
First Posted : October 19, 1999
Last Update Posted : June 24, 2005
Oregon Health and Science University
Information provided by:
National Center for Research Resources (NCRR)

Brief Summary:

OBJECTIVES: I. Examine the concentration of docosahexanoic acid (DHA) and other n-3 fatty acids in plasma, erythrocyte, and adipose tissue in patients with various forms of retinitis pigmentosa and Usher syndrome.

II. Determine the synthesis and catabolism of DHA from linolenic acid in these patients.

III. Determine the synthesis, absorption, and catabolism of DHA under different dietary conditions in these patients.

Condition or disease
Usher Syndrome Retinitis Pigmentosa

Detailed Description:

PROTOCOL OUTLINE: Patients may participate in one or more of the arms of this study.

Arm I (adipose tissue study): Adipose tissue is collected from the buttocks of patients with Usher II retinitis pigmentosa (RP), patients with non-Usher RP, and control subjects. Dietary histories are obtained from all patients and subjects.

Arm II (isotope study): Patients meeting the same criteria as in arm I receive oral D5-labeled linolenic acid and oral D4-labeled linolenic acid that is dissolved in oil and incorporated into foods. Subjects must avoid eating fish and shellfish during the 35 days of the isotope study. Blood samples are collected at 0, 8, 24, and 48 hours, daily on days 3-7, and then on days 10, 18, and 35.

Arm III (flaxseed oil feeding): Patients with all types of RP and control subjects receive flaxseed oil, a form of linolenic acid, for 12 weeks. Subjects may also receive high oleic safflower oil or olive oil as a control fat for 12 weeks. Subjects complete a diet history at the end of each fatty acid supplementation period. All subjects must follow a diet free of seafood and fish oil supplements.

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Study Type : Observational
Enrollment : 100 participants
Primary Purpose: Screening
Study Start Date : October 1999

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes


  • Retinitis pigmentosa, including: Usher syndrome (types I and II) Simplex
  • The following inheritance patterns eligible: X-linked recessive; Autosomal dominant; Autosomal recessive

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00004345

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United States, Oregon
Oregon Health Sciences University
Portland, Oregon, United States, 97201-3098
Sponsors and Collaborators
National Center for Research Resources (NCRR)
Oregon Health and Science University
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Study Chair: William Connor Oregon Health and Science University

Layout table for additonal information Identifier: NCT00004345     History of Changes
Other Study ID Numbers: 199/11904
First Posted: October 19, 1999    Key Record Dates
Last Update Posted: June 24, 2005
Last Verified: July 2002

Keywords provided by National Center for Research Resources (NCRR):
Usher syndrome
ophthalmologic disorders
rare disease
retinitis pigmentosa

Additional relevant MeSH terms:
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Usher Syndromes
Retinitis Pigmentosa
Pathologic Processes
Retinal Diseases
Eye Diseases
Eye Diseases, Hereditary
Retinal Dystrophies
Retinal Degeneration
Genetic Diseases, Inborn
Deaf-Blind Disorders
Hearing Loss
Hearing Disorders
Ear Diseases
Otorhinolaryngologic Diseases
Hearing Loss, Sensorineural
Sensation Disorders
Neurologic Manifestations
Nervous System Diseases
Vision Disorders
Abnormalities, Multiple
Congenital Abnormalities
Signs and Symptoms