Inclusion Criteria:  Older HIV-positive cohort (n=500):  documented HIV infection age >50 years at study entry Korean ethnicity likely route of HIV acquisition via sexual exposure by male to male exposure able to comprehend study patient information leaflet. Virologically suppressed subjects Subjects with primary HIV infection are eligible and investigators are encouraged to recruit such subjects. Our target population (those infected with HIV via sexual routes of men who have sex with men) has been chosen as this group represent the vast majority of older HIV-positive individuals attending for care in Korea; analyses of other groups (e.g. injection drug users, those infected through blood/blood products and transgender individuals), who may have very different needs and outcomes, would likely be under-powered.  Younger HIV-positive cohort (n=250):  documented HIV infection age <50 at study entry* Korean ethnicity likely route of HIV acquisition via sexual exposure by male to male exposure able to comprehend study patient information leaflet * this group will comprise of at least 70 subjects in each of the following age groups: 20-29, 30-39, 40-49 years. Recruitment will be monitored by the Study Monitoring Team  HIV-negative cohort (n=250):  documented negative HIV test at screening age >50 years at study entry Korean ethnicity self reported sexual preferences of men who have sex with men  To enroll matched control, we will try to match age, sexual orientation, and participating clinic.  Exclusion Criteria:  in the opinion of the investigator, those unable or unwilling to comply with the requirements of the study life expectancy less than 6 months