The key genes associated with sarcopenia include Apoal, Apoe, Apoa 2, Rpl 21, Nefm, Cd 9, Rpl 6, and Cd 81. Among them, CD 9 may be a new biomarker for sarcopenia. Dapoxetine, levomilnacipran, and milnacipran can target CD9 and are expected to become drugs for the treatment of sarcopenia. Here, CD9 is linked to sarcopenia.