The purpose of the study is to collect information on disease characteristics from adult patients diagnosed with fatty acid oxidation disorders (FAOD).

In this study there will be no drug intervention. The study will include a Baseline visit and a follow up visit scheduled at Month 4. At these visits medical history, safety assessments, concomitant medications, exercise tests and quality of life questionnaire data will be collected.

Inclusion Criteria:

1. A genetically confirmed diagnosis of one of the following:

   1. Carnitine palmitoyltransferase 2 deficiency
   2. Very long-chain Acyl-CoA dehydrogenase deficiency
   3. Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency
   4. Trifunctional protein deficiency

2. A stable treatment regimen for at least 30 days

3. Ambulatory and able to perform the study exercise test, using walking aids if necessary

4. Willing and able to personally sign and date an informed consent document indicating that the subject has been informed of all pertinent aspects of the study

Exclusion Criteria:

1. Unstable or poorly controlled disease as determined by one or more of the following:

   1. Presence of symptoms of acute rhabdomyolysis with clinically significant elevations in serum CK
   2. Evidence of acute crisis from their underlying disease

2. Currently taking a PPAR agonist

3. Have motor abnormalities other than those related to the fatty acid oxidation disorder that could interfere with the study procedures, as determine by the investigator

4. Evidence of significant concomitant medical or psychiatric disease that in the opinion of the Investigator may interfere with the conduct or safety of this study

5. Pregnant or nursing females

Patients will be recruited from centres experienced in the identification and subsequent management of patients with long chain FAOD.