• Male and female participants 2 to \< 18 years of age with a diagnosis of PNH confirmed by high-sensitivity flow cytometry with red blood cells (RBCs) and with white blood cells granulocytes/monocytes clone size ≥ 10%. The minimum body weight for patients in Cohort 1 is 35 kg.

• Patients being treated with anti-C5 therapy and who have been on a stable regimen (dose and interval) for at least 6 months prior to enrollment, may be screened and enrolled in the study and switched to iptacopan irrespective of their anemia and hemolysis status, at the discretion of the Principal Investigator.

• Patients who are anti-C5 treatment naive: mean hemoglobin level \< 10 g/dL confirmed by central laboratory assessment during screening.

• Patients who are anti-C5 treatment naive: lactate dehydrogenase (LDH) \> 1.5 × upper limit of normal (ULN) documented by at least 2 laboratory measurements 2 to 6 weeks apart during the screening period, one of which is to be done by the central lab.

• Vaccination against Neisseria meningitidis and Streptococcus pneumoniae infection is required prior to the start of study treatment. If the participant has not been previously vaccinated, or if a booster is required, vaccine should be given according to local guidelines at least 2 weeks prior to first study drug administration. If study treatment has to start earlier than 2 weeks post-vaccination, prophylactic antibiotic treatment should be initiated.

• Vaccination against Haemophilus influenzae is recommended, according to local guidelines, at least 2 weeks before iptacopan.