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

This study has been terminated.
Oregon Health and Science University
Information provided by:
National Center for Research Resources (NCRR) Identifier:
First received: October 18, 1999
Last updated: June 23, 2005
Last verified: July 2002

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.

Usher Syndrome Retinitis Pigmentosa

Study Type: Observational
Study Design: Primary Purpose: Screening

Resource links provided by NLM:

Further study details as provided by National Center for Research Resources (NCRR):

Estimated Enrollment: 100
Study Start Date: October 1999
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.


Ages Eligible for Study:   Child, Adult, Senior
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
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Please refer to this study by its identifier: NCT00004345

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
Study Chair: William Connor Oregon Health and Science University
  More Information Identifier: NCT00004345     History of Changes
Other Study ID Numbers: 199/11904
Study First Received: October 18, 1999
Last Updated: June 23, 2005

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

Additional relevant MeSH terms:
Retinitis Pigmentosa
Usher Syndromes
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 processed this record on August 16, 2017