• Male or female participants, 6 to \<12 years of age at screening

• HeFH diagnosed either by genetic testing or on phenotypic criteria

• Fasting LDL-C \>130 mg/dL (3.4 mmol/L) at screening

• For participants 8 to \<12 years, on an optimal dose of statin (investigator's discretion) unless statin intolerant, with or without other lipid-lowering therapy (e.g. ezetimibe). For participants \<8 years, the use of background lipid-lowering treatment is based on investigator's discretion.

• Participants on lipid-lowering therapies (such as statin and/or e.g. ezetimibe) must be on a stable dose for ≥30 days before screening with no planned medication or dose changes during study participation.