Inclusion Criteria:  Diagnosis of LC-FAOD including: carnitine palmitoyltransferase (CPT I or CPT II) deficiency, very long chain acyl-CoA dehydrogenase (VLCAD) deficiency, long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency, trifunctional protein (TFP) deficiency, or carnitine-acylcarnitine translocase (CACT) deficiency. Willing and able to provide consent or, if a minor, provide assent and informed consent by their legally authorized representative. Access to the internet and an internet-enabled device. Reside in the geographical regions where the platform is supported and approved by applicable IRB/IEC and /or health authority. Not receiving triheptanoin through an Ultragenyx-sponsored interventional clinical trial or Ultragenyx Investigator Sponsored Trial (IST). NOTE: Individuals are eligible to participate in this online DMP if they previously participated in UX007 clinical trials, are currently participating in the in clinic UX007-CL401 (NCT04632953), are receiving triheptanoin through Expanded Access or Compassionate Use programs, or are receiving commercially available triheptanoin via prescription.