Cross-sectional cohort study of participants with HIV with or without protocol-defined Fanconi syndrome (confirmed creatinine clearance [CLcr] decline and evidence of proximal tubulopathy).

Inclusion Criteria - Fanconi Cases

Subjects must meet all of the following inclusion criteria to be eligible for participation in this study.

• Adult (greater than or equal to 18 years) HIV-1 infected subjects regardless of race or ethnicity.
• Subjects must be on a stable ARV regimen for greater than or equal to 1 month prior to study entry.
• Evidence of protocol-defined Fanconi syndrome
• TDF subjects must be on TDF-containing regimen at the time of onset of Fanconi syndrome.
• Negative serum pregnancy test (females of child-bearing potential only).
• Less than two years post-menopausal women of child-bearing potential (TDF subjects only) agree to follow an adequate birth control barrier method or agree to abstain from heterosexual intercourse while participating in the study.
• The ability to understand and sign a written informed consent form, which must be obtained prior to initiation of any study procedures.

Exclusion Criteria - Fanconi Cases

Subjects who meet any of the following exclusion criteria are not to be enrolled in this study.

• Non TDF subjects who have received any TDF within the prior 6 months, or those who have received greater than 2 weeks cumulative treatment.
• TDF subjects who have previously served as a TDF control for this protocol.
• History of current alcohol or substance abuse judged by the investigator to potentially interfere with laboratory results.

Inclusion Criteria - Controls

Subjects must meet all of the following inclusion criteria to be eligible for participation in this study.

• Adult (greater than or equal to 18 years) HIV-1 infected subjects regardless of race or ethnicity.
• No evidence of protocol-defined Fanconi syndrome
• On a TDF-containing regimen matched to a Fanconi case by clinic location, duration on TDF and age.
• Negative serum pregnancy test (females of child-bearing potential only).
• The ability to understand and sign a written informed consent form, which must be obtained prior to initiation of any study procedures.

Exclusion Criteria - Controls

Subjects who meet the following exclusion criteria are not to be enrolled in this study.

• History of current alcohol or substance abuse judged by the investigator to potentially interfere with laboratory results.

HIV infected subjects with protocol defined Fanconi Syndrome