Twin study aims to unlock secrets of metabolic syndrome and liver disease

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria 1\. Age between 15 and 44 years. 2. Provision of informed consent to participate in the study. 3. Twin with a living co-twin. 4. Positive family history in first- and second-degree relatives of metabolic syndrome (MS), associated diseases, or the most common complications of the syndrome. \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Exclusion Criteria Permanent exclusion criteria: 1. Co-twin does not consent to participate in the study. 2. Inability to obtain medical history of biological family members. 3. Presence of advanced liver fibrosis, cirrhosis, or liver cancer. 4. Known liver genetic disorders, autoimmune hepatitis, celiac disease, hemochromatosis, primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), cystic fibrosis, or Wilson's disease. 5. Current or chronic alcohol consumption \>20 g of ethanol/day in women and \>30 g/day in men. 6. Short bowel syndrome. 7. Cyanotic congenital heart defect. 8. Myasthenia. 9. Central nervous system degenerative diseases such as Alzheimer's disease, Parkinson's disease, or Huntington's disease. 10. Storage diseases involving the liver. 11. Active malignant neoplasm undergoing treatment (excluding non-melanoma skin cancers and melanoma treated non-pharmacologically). 12. Chronic kidney disease requiring renal replacement therapy. 13. Status post organ or tissue transplantation requiring immunosuppression. 14. Pituitary, hypothalamic, or adrenal hyperfunction/hypofunction requiring hormone supplementation. 15. Addiction to psychoactive substances or drugs. 16. Other severe and incurable diseases that, in the investigator's opinion, constitute a permanent contraindication for participation in the study. 17. Lack of cooperation by the volunteer during the visit to the Research Center. \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Temporary exclusion criteria (after resolution, the volunteer may be enrolled): 1. Acute infection, low-grade fever or fever, or use of antibiotics at the time of recruitment or prior to the visit at the Research Center - inclusion possible after 6 weeks. 2. Any vaccination within the past 6 weeks. 3. Pregnancy and up to 6 months postpartum. 4. 3 months after the natural cessation of breastfeeding. 5. 3 months after surgery (does not apply to minor surgical procedures). 6. Untreated hyperthyroidism or hypothyroidism - inclusion possible 3 months after achieving euthyroidism. 7. Significant weight loss or gain in the past 3 months (\>10% of initial body weight) - inclusion possible 3 months after weight stabilization. 8. 6 months after discontinuation of temporary parenteral or enteral nutrition via feeding tube. 9. 12 months after bariatric surgery. 10. Systemic treatment with steroids, chemotherapy, immunosuppressive drugs, or biological therapy known to be hepatotoxic or potentially inducing abnormalities found in MS - inclusion possible at least 3 months after completing therapy.