LOWER: Lomitapide Observational Worldwide Evaluation Registry

Inclusion Criteria: * Patients of all ages, including minors, who have initiated commercial treatment with lomitapide prior to or at time of registry enrolment. * Patients who have the ability to understand the requirements of the study and provide written informed consent to comply with the study data collection procedures or paediatric patients with the consent of a parent or legal guardian. Patients ≥7 years of age (or above the age determined by the IRB/EC and in accordance with the local regulations and requirements) must also provide written informed assent forms. Exclusion Criteria: * Patients who are receiving lomitapide in clinical trials or through compassionate use, where patients are followed under a separate protocol. * Patients receiving an investigational agent, defined as any drug or biologic agent other than lomitapide that has not received market authorization in the country of participation, at time of lomitapide initiation and continuing to receive an investigational agent at time of registry enrolment. These patients may be enrolled if receiving lomitapide when the investigational agent is discontinued..