The purpose of this Phase 1b study is to assess REN001 safety in subjects with fatty acid oxidation disorders.

This is a Phase 1b, open-label, multiple-dose study of the safety and tolerability of 2 dose levels of REN001 in subjects with fatty acid oxidation disorders (FAODs) with confirmed mutations in the Carnitine palmitoyltransferase II deficiency (CPT2), Very long-chain Acyl-CoA dehydrogenase deficiency (VLCAD), Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHAD) or Trifunctional Protein Deficiency (TFP). All subjects will provide written consent prior to commencing any study related activities or assessments. Potential subjects will be screened for study participation up to 8 weeks prior to the start of dosing.The study is divided into two parts, Part A and Part B. Part A has finished enrollment and further eligible patients will participate in Part B only.

Inclusion Criteria:

Subjects must give written, signed and dated informed consent

Confirmed diagnosis of FAOD

A diagnostic acylcarnitine profile, in blood or cultured fibroblasts

A stable treatment regimen for at least 30 days prior to enrollment

Exclusion Criteria:

Unstable or poorly controlled disease

Treatment with an investigational drug within 1 month or within 5 half-lives, whichever is longer

Have been hospitalized within 3 months prior to screening for any major medical event

Pregnant or nursing females