The purpose of this study is to assess the prevalence of metabolic and physical abnormalities in HIV infected (via mother-to-child transmission) and uninfected children and youth. Metabolism, body composition, bone density, and other factors will be assessed in relationship to participants' exposure to highly active antiretroviral therapy (HAART).

Despite advances in HIV care associated with HAART, many patients on HAART regimens develop physical and metabolic problems, including changes in body fat distribution (lipodystrophy), osteopenia and osteoporosis, dyslipidemia, and hyperlactatemia. Early studies suggest that protease inhibitors (PIs) were directly responsible for HIV Lipodystrophy Syndrome (HLS) and skeletal complications in HAART-treated patients. This study will compare HIV infected, HAART-treated children and youth and their uninfected counterparts to make connections between HAART, HLS, and skeletal and metabolic problems. The study is the first to address the prevalence and risk assessment of these complications in children, and will be useful in predicting long-term prognosis in HIV patients who use or have used HAART.

There will be three groups in the study. Group 1 participants will be uninfected volunteers who will receive no protocol-specific treatment or other intervention. Vertically infected HIV patients in Groups 2 and 3 will continue their current HAART either on a non-PI-containing regimen (Group 2) or a PI-containing regimen (Group 3). Screening evaluations will be conducted within 30 days prior to study entry. Study evaluations may be completed at study entry or over the course of up to 3 study visits. All participants will undergo whole body and regional DEXA scans (to assess bone density), measurements to determine sexual maturity, and blood work.

Inclusion Criteria

For HIV uninfected participants (Group 1)

• HIV-1 negative (perinatally HIV-exposed but uninfected participants are eligible)

For HIV infected participants (Groups 2 and 3)

• Mother-to-child (vertically) transmitted HIV infection
• Confirmed diagnosis of HIV-1 infection by two positive assays from two different samples
• For Group 2, cannot have taken a PI-containing regimen in the 12 months prior to study entry or have ever received a PI for 2 or more weeks
• For Group 3, must currently be taking the same PI-containing regimen taken continuously for at least 12 months prior to study entry

For all participants

• Accessible medical and medications history
• Parent, legal guardian, or participant willing to give informed consent and willing to comply with study requirements
• Females who have begun menstruating must have negative pregnancy test

Exclusion Criteria

• Receipt of certain medications, including growth hormone, megestrol acetate, anabolic agents, anticytokine agents, systemic ketoconazole, systemic glucocorticoids (except if receiving stable physiologic doses), or drugs to treat osteoporosis
• Type II diabetes mellitus and unable to omit medication prior to specimen collection
• Pregnancy within the last 12 months, currently pregnant, or breastfeeding
• History of eating disorder