The SARC-F showed a significant association with economic class, with patients in classes D and E having a higher proportion of sarcopenia risk (p = 0.007), regular smoking (p = 0.006), AIDS diagnosis (p < 0.001), presence of opportunistic infections (p = 0.002), CD4 T-cell count ≤ 200 cells/mm3, and low muscle strength (p < 0.001). The gene discussed is CD4; the disease is AIDS.