PIGN and HIV infectious disease: In contrast to some studies, we found no significant associations between levels of these mitokines with sex [21], antiretroviral class usage [22], or viral load [23]; however, we did note negative correlations between current CD4 counts with FGF21 and GDF15 values, especially within the MDC4 group, potentially further linking mitokines to composition of immune cells post-HIV infection with metabolic dysfunction, as suggested previously for FGF21 [19].