Gene Mutation Linked to Obesity Found to Protect Against Heart Disease

A large-scale genetic study published in Nature Medicine has uncovered a surprising paradox: a gene mutation known to cause severe obesity appears to significantly reduce the risk of heart disease and abnormal cholesterol levels among those who carry it. The finding offers new insight into the complex relationship between obesity and cardiovascular health.

Obesity is typically associated with higher cholesterol, elevated blood pressure, and increased risk of heart disease. However, researchers at the University of Cambridge analyzed genetic data from thousands of individuals with obesity and found that people whose obesity is caused by a rare variant in the MC4R gene actually have lower levels of LDL ("bad") cholesterol, blood pressure, and triglycerides—and a notably lower rate of heart disease—despite having similar body mass indexes to others.

The MC4R gene encodes a protein in the brain that suppresses hunger and regulates appetite. Mutations in this gene disrupt that mechanism, leading to weight gain. Around 1% of adults and 5% of children with obesity carry such mutations.

Using data from major resources including the Obesity Genetics Study and the UK Biobank, the team compared health outcomes between MC4R mutation carriers and those with normal gene function. The results showed that carriers tend to have healthier lipid profiles and lower cardiovascular risk. Further metabolic analysis suggested that people lacking normal MC4R function process dietary fats differently, which may help explain their unexpected protection against heart disease.