Study to Assess the Efficacy, Pharmacokinetics, Safety and Tolerability of Iptacopan in Pediatric Patients With Primary IgAN

The study will enroll approximately 34 pediatric patients with a diagnosis of primary IgAN by kidney biopsy performed within 3 years of Screening with \< 50% tubulointerstitial fibrosis and \<25% crescents and not previously treated with immunosuppressive or other immunomodulatory agents within 90 days (or 180 days for rituximab) prior to first study drug administration. The study comprises the following periods: * Screening Period (up to 11 weeks) * Run-in Period (2 weeks): This period will be approximately 14 days prior to the Enrollment Visit (Day 1) to obtain Baseline assessments, including two UPCR FMV measurements (required prior to Day 1). * Treatment Period ( 52 weeks): The study will enroll approximately 34 pediatric patients in a staggered manner. The approach will be to first enroll Cohort 1 (12 to \< 18 years of age) to collect safety data (including CV surveillance data), tolerability data, PK data and biomarker data for up to 52 weeks (EOS). Cohort 1 participants will be enrolled in a single group of 22 participants. Cohort 2 (2 to \< 12 years of age) participants will be enrolled in 2 groups with a total 12 participants. * Follow-up Period (1 week): Participants who completed the Week 52 (EOS) visit and meet all the eligibility criteria may be enrolled in a rollover extension program (REP) in which they will receive open-label iptacopan. Participants who do not enroll in the REP or do not complete Day 1 of the REP within 7 days of the EOS, should be contacted 7 days after the EOS visit for AE and SAE monitoring and any AEs reported by the participant should be recorded in the study case report form (CRF).