Men live shorter lives compared with women. We have discovered a genetic mutation can help explain this sex difference. The mutation is called LOY, which is an abbreviation for 'Loss Of chromosome Y' and it occurs during lifetime in aging men. Since the Y chromosome is present in men but not in females this mutation is male specific. LOY is more common in older compared to younger men and smoking is a strong risk factor. We have previously shown that men with LOY in their blood cells have an increased risk to be diagnosed with and even die from many different types of common disease. In the present project, we are planning to investigate the effects from LOY in a large population based cohort. It is our hope that LOY can be used in future medicine for improved diagnostics and treatment of common human disease.