The REGGI registry is a prospective, multicenter observational registry in Russia designed to collect data on patients with extreme hypertriglyceridemia (triglyceride levels ≥10 mmol/L). The registry aims to describe the clinical, demographic, and molecular-genetic characteristics of patients, as well as current diagnostic approaches and treatment patterns in real-world practice. The collected data may inform future research and support improvements in patient care.

Hypertriglyceridemia (HTG) is associated with an increased risk of atherosclerotic cardiovascular disease, acute pancreatitis, and all-cause mortality. The risk increases with higher triglyceride levels and is most significant in extreme HTG (triglyceride concentration ≥10 mmol/L). Epidemiological studies in the Russian Federation report a prevalence of extreme HTG of approximately 0.1-0.2% (146,000-292,000 individuals). Extreme HTG can have monogenic or polygenic (multifactorial) origins, which influences the clinical course of the disease.

Written informed consent is obtained from the patient or their legal guardian prior to inclusion.

Data sources include routine diagnostic findings and medical records. Participating sites monitor patients' clinical status as part of routine medical care. There are no interventions in this registry: medications are not changed, no invasive procedures are performed, and no study-specific interventions or procedures associated with additional risk are performed. Only clinical course, laboratory results, lipid profile, and therapeutic measures are documented, including any genetic testing if available.

Patients are followed annually or more frequently if clinically indicated. There is no minimum or maximum age for inclusion, and follow-up duration is not predefined and depends on clinical practice. Participation is voluntary, and patients may withdraw at any time without affecting their medical care. Data are pseudonymized and can be decrypted using a separately maintained key list; data can be deleted upon patient request.

Inclusion Criteria:

• Patients with extreme hypertriglyceridemia (triglyceride levels ≥10 mmol/L), confirmed by at least two independent measurements.
• Written informed consent from the patient or legal guardian.
• No age restrictions.

Exclusion Criteria:

• Patients whose extreme hypertriglyceridemia is caused by alcohol abuse, uncontrolled diabetes, or other medical conditions, unless extreme hypertriglyceridemia is confirmed after controlling the underlying condition.
• Lack of informed consent.

Patients with extreme hypertriglyceridemia (triglyceride levels ≥10 mmol/L) who are receiving care at participating lipid centers in the Russian Federation. Both pediatric and adult patients are eligible. Data collection includes routine clinical assessments, laboratory tests, lipid profiles, and genetic analyses if available. Participation is voluntary, and patients may withdraw at any time without affecting their medical care.