This is a multi-center, open-label study for FCS participants rolling over from the ISIS 304801-CS6 (NCT02211209) index study, FCS participants rolling over from the ISIS 304801-CS16 (NCT02300233) index study and Treatment-naïve group. All participants were to receive volanesorsen 300 milligrams (mg) once per week for 52 weeks. Participants were allowed dose adjustment/dose reduction based on monitoring rules. Participants had the option of continuing dosing for an additional 52 weeks (France: up to an additional 104 weeks for a total of 156 weeks) until an expanded access program was approved and available in their country. Participants who were not participating in an expanded access program were to enter a 13-week (France: 26-week) post-treatment evaluation period.