The changes affecting the conduct of the study are summarized below. 1. The number of study sites increased to approximately 8 sites globally to allow for additional enrollment. 2. The number of subjects planned increased from 20 to 30. 3. The study population was expanded to include a cohort of subjects aged 6 months – 6 years of age. The upper age limit for the study was increased to 35 years of age. 4. The inclusion criteria were modified to include the following: • Male or female, 6 months –35 years of age • Willing and able to provide access to medical records charting the last 18-24 months of care prior to the study initiation, or from birth for those subjects less than 18 months of age • Have severe LC-FAOD, as evidenced by ANY ONE of the following significant clinical manifestations despite management: Episodic Elevated creatine kinase (CK) with Reported Muscle Dysfunction: Episodes of elevated CK levels over the last 6 months -1 year (defined as ≥ 2X upper limit of age/gender-matched normal, or ≥ 500 units/L if age-matched reference is not established), AND patient report of frequent muscle pain and muscle fatigue, exercise intolerance, or limitation of • Frequent Severe Major Medical Episodes (at least 3 within the past year, or 5 within 2 years) of hypoglycemia, rhabdomyolysis, or exacerbation of cardiomyopathy (CM), requiring ER/acute care visits or hospitalizations 5. Specific language regarding stopping rules was modified to remove language suspending enrollment if two subjects develop the same Grade 3 AE that is unexpected and possibly, probably, or definitely related to study drug, or if any subject develops a Grade 4 AE that is unexpected and possible, probably, or definitely related to study drug. 6. The requirement for subjects to return all unused study drug, and for site personnel to estimate the remaining volume of unused medication, was removed.

(continued) 7. To specify procedures and age-specific assessments in subjects < 6 years of age, an additional Schedule of Events (Table 2.2: Schedule of Events for Subjects < 6 years of Age) was inserted. An additional assessment of growth was obtained at the Screening Visit. The Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT), SF-10/SF-12 assessments at the Screening Visit were unnecessary and removed. 8. Skeletal Myopathy Efficacy Measures were modified as follows: • Exercise Intolerance. During cycle ergometry, additional monitoring of blood pressure, pain and perceived exertion, and biochemical markers will be conducted as specified in the Clinical Evaluator’s Manual. The OMNI scale will be used in place of the Borg scale to measure perceived exertion. The Faces Pain Scale – Revised (or visual analog scale) will be used as an age-appropriate measure of perceived muscle pain. The requirement for the dose and standard macronutrient meal 2 hours prior to cycle ergometry has been relaxed to “approximately 2 hours”. Subjects will be fed a standardized macronutrient meal including either MCT (at the Screening and Baseline Visits, if applicable) or UX007 (all visits post-Baseline), approximately 2 hours prior to test administration. Subjects and/or caregivers will report activity level in the electronic diary at each incidence of muscle pain/leg cramps and muscle weakness/fatigue. Subjects and/or caregivers will report the number of episodes or events of muscle pain and leg cramps on exertion in the electronic diary on a daily basis.

(#8, continued) • Muscle Function and Motor Development. Subjects will be required to consume study drug (or MCT during the Run-in period, if applicable) and a standard macronutrient meal approximately 2 hours prior to the 12MWT. The OMNI scale will be used in place of the Borg scale to measure perceived exertion. The Faces Pain Scale (subjects < 18 years) or visual analog scale (subjects ≥ 18 years) will be used to measure perceived muscle pain. Respiratory rate has been removed as an assessment during the 12MWT. Subjects < 6 years of age will not perform the 12MWT. The Peabody Developmental Motor Scales – 2nd Edition (PDMS-2) has been added as an age-appropriate measure of gross motor development in subjects < 6 years of age. Subjects will be required to consume study drug and a standard macronutrient meal approximately 2 hours prior to testing with the PDMS-2. 9. LC-FAOD Laboratory Measures were modified as follows: • An additional serum sample, designated for exploratory biomarker research, will be collected at the Baseline and Week 24 visits. • Inflammatory cytokines will not be specifically assessed, but may be investigated as part of the additional research sample. • Plasma heptanoate will be assessed as a pharmacokinetic (PK) metabolite 10. An additional measurement of head circumference was included as a growth parameter in subjects aged ≤ 36 months at each visit. 11. Acceptable methods of contraception, including abstinence, were specified for females and males of childbearing potential. 12. Additional safety monitoring calls were included within 36 hours following the completion of each 12MWT, and within 36 hours of any cycle ergometer test not associated with post-test blood to assess AEs related to the 12MWT or cycle ergometer test. 13. The 3-day diet history was modified as a paper diary (previously electronic). The requirement to maintain a 3-day diet history following any dose-adjustment was deleted.

(continued) 14. Additional information on electronic diary data capture was added. 15. Contact information for calls related to serious AEs was provided for BioSoteria, the Medical Monitor.

The changes affecting the conduct of the study are summarized below. 1. The study population was expanded to include subjects diagnosed with trifunctional protein (TFP) deficiency. The Inclusion and Exclusion Criteria were modified to reflect this change. 2. Subjects were required to consume study drug (or MCT at the Baseline visit, if applicable) and a standard macronutrient meal approximately 2 hours prior to the PDMS-2 test to assess subjects in the post-absorptive state. 3. Fasting serum glucose collection was specified after a 4 hour fast, or as tolerated by subjects at the discretion of the PI. 4. Blood sample collection for PK of UX007 and UX007 metabolites was specified for 2-hours after a standardized macronutrient meal including either MCT (at Run-in or Baseline, if applicable) or UX007 (all visits post-Baseline).

The changes affecting the conduct of the study are summarized below. 1. The number of study sites was increased to approximately 10 sites globally to support enrollment. 2. The study population was expanded to included subject over age 35. The upper age limit for the study was removed from the Inclusion Criteria. 3. Additional chronic toxicity studies in mini-pigs was added to the nonclinical summary. 4. Subjects who will reach 6 years old within 6 months of the Baseline visit were added for consideration for the cycle ergometry assessments. 5. The criteria for the 12MWT were expanded to include subjects who reach 6 years old during the study or achieve mastery of all PDMS-2 skill sets. 6. In order to minimize patient burden, additional language was placed to specify that the Clinical Evaluator, Investigator, and Sponsor would assess the requirement of additional PDMS-2 assessments during the study for those subjects that have already demonstrated a mastery of the skills that are being measured. 7. The description of the Data Monitoring Committee was clarified.

The changes affecting the conduct of the study are summarized below. 1. Pancreatic lipase inhibitors were added to the list of prohibited medications following in vitro studies demonstrating that pancreatic lipases hydrolyze triheptanoin. Oral salicylates were removed from the list of prohibited medications. 2. The use of electronic diaries was discontinued due to unexpected performance issues. Paper diaries replaced the electronic diaries and captured the same data; therefore, references to electronic diary use were removed. 3. Interim analysis at Week 48 was removed.