Any untoward medical occurrence in a participant who received study drug was considered an adverse event (AE) without regard to possibility of causal relationship with this treatment. TEAEs were defined as AEs that developed or worsened during TEAE period (period from the first administration of study drug in ACT13739 through the last administration of the study drug in the combined ACT13739/LTS14116 treatment period plus 1 month or end of study participation for participant, whichever occurred first). For this analysis, baseline was defined as initial ACT13739 study baseline.

Criteria for potentially clinically significant abnormalities: * Hemoglobin: less than or equal to (\<=) 115 grams per liter (g/L); greater than or equal to (\>=)185 g/L; decreased from baseline (DFB) \>=20 g/L * Hematocrit: \<=0.37 volume/volume (v/v); \>=0.55 v/v * Erythrocytes: \>=6 Tera/L * Platelets: lesser than (\<) 100 Giga/L; \>=700 Giga/L * Leukocytes: \<3.0 Giga/L (Non-Black \[NB\]) or \<2.0 Giga/L (Black \[B\]); \>=16.0 Giga/L * Neutrophils: \<1.5 Giga/L (NB) or \<1.0 Giga/L (B); * Lymphocytes: greater than (\>) 4.0 Giga/L * Monocytes: \>0.7 Giga/L * Basophils: \>0.1 Giga/L * Eosinophils: \>0.5 Giga/L or \>upper limit of normal (ULN) (if ULN \>=0.5 Giga/L) For this analysis, baseline was defined as initial ACT13739 study baseline.

Criteria for potentially clinically significant abnormalities: * Sodium: \<=129 millimoles (mmol)/L; \>=160 mmol/L * Potassium: \<3 mmol/L; \>=5.5 mmol/L * Chloride: \<80 mmol/L; \>115 mmol/L.

Criteria for potentially clinically significant abnormalities: * Alanine Aminotransferase (ALT): \>3 ULN; \>5 ULN; \>10 ULN and \>20 ULN * Aspartate aminotransferase (AST): \>3 ULN; \>5 ULN; \>10 ULN and \>20 ULN * Alkaline phosphatase: \>1.5 ULN * Bilirubin: \>1.5 ULN; \>2 ULN.

Criteria for potentially clinically significant abnormalities: * Glucose: \<=3.9 mmol/L and \< lower limits of normal (LLN); \>=11.1 mmol/L (unfasted \[unfas\]) or \>=7 mmol/L (fasted \[fas\]) * Lipase: \>= 3 ULN * C Reactive Protein (CRP): \> 2 ULN or \> 10 milligrams (mg)/L (if ULN not provided).

Criteria for potentially clinically significant abnormalities: * Creatinine: \>=150 micromoles per liter (mcmol/L) (Adults); \>=30% change from baseline; \>= 100% change from baseline * Blood urea nitrogen: \>=17 mmol/L * Urate: \<120 mcmol/L; \>408 mcmol/L For this analysis, baseline was defined as initial ACT13739 study baseline.

Criteria with potentially clinically significant urine abnormalities: pH: \<= 4.6; pH: \>= 8.0

Criteria for potentially clinically significant vital sign abnormalities: * Systolic blood pressure (SBP) supine: \<=95 millimeters of mercury (mmHg) and DFB \>=20 mmHg; \>=160 mmHg and increase from baseline (IFB) \>=20 mmHg * Diastolic blood pressure (DBP) supine: \<=45 mmHg and DFB \>=10 mmHg; \>=110 mmHg and IFB \>=10 mmHg * Heart rate (HR) supine: \<=50 beats per minute (bpm) and DFB \>=20 bpm; \>=120 bpm and IFB \>=20 bpm * Weight: \>=5% DFB; \>=5% IFB For this analysis, baseline was defined as initial ACT13739 study baseline.

Criteria for potentially clinically significant ECG abnormalities: * ECG mean HR: \<30 bpm; \<30 bpm and DFB \>=20 bpm; \<40 bpm; \<40 bpm and DFB \>=20 bpm; \<50 bpm; \<50 bpm and DFB \>=20 bpm; \>90 bpm; \<90 bpm and DFB \>=20 bpm; \>100 bpm; \<100 bpm and DFB \>=20 bpm; \>120 bpm; \<120 bpm and DFB \>=20 bpm * PR Interval: \>200 milliseconds (ms); \>200 ms and IFB \>=25%; \>220 ms; \>220 ms and IFB \>=25%; \>240 ms; \>240 ms and IFB \>=25% * QRS duration: \>110 ms; \>110 ms and IFB \>=25%; \>120 ms; \>120 ms and IFB \>=25% * QTc Bazett (QTcB) interval: \>450 ms; \>480 ms; \>500 ms; IFB \>30 and \<=60 ms, IFB \>60 ms * QTc Fridericia (QTc F): \>450 ms; \>480 ms; \>500 ms; IFB \>30 and \<=60 ms; IFB \>60 ms * QT Interval: \>500 ms For this analysis, baseline was defined as initial ACT13739 study baseline.

Skin biopsies taken at Baseline and Week 26 were analyzed for cellular GL-3 accumulation (inclusions) by light microscopy. Three independent pathologists evaluated each biopsy using an inclusion severity score of 0 (none/trace), 1 (mild), 2 (moderate), and 3 (severe), where higher score indicated more severe condition. A single score per participant per time point was derived by taking the score rated by a majority of the pathologists; if a majority score could not be derived, the median score was used. Data were summarized and reported in terms of number of participants with shift from Baseline GL-3 score to Week 26 GL-3 score. Any shift category of Baseline score/Week 26 score that was not observed is not reported. Shift to lower score from Baseline to Week 26 indicates less severe condition at Week 26.

Skin biopsies taken at Baseline and Week 26 were analyzed for cellular GL-3 accumulation (inclusions) by light microscopy. Three independent pathologists evaluated each biopsy using an inclusion severity score of 0 (none/trace), 1 (mild), 2 (moderate), and 3 (severe), where higher score indicated more severe condition. A single score per participant per time point was derived by taking the score rated by a majority of the pathologists; if a majority score could not be derived, the median score was used. Change from Baseline in GL-3 score was obtained by subtracting Baseline value from post-baseline value at Week 26. A negative change from Baseline indicates less severe condition at Week 26.