Aging is associated with decreased secretion of most myokines,including IGF-1, irisin, IL-15, apelin, IL-6, brain-derived neurotrophic factor (BDNF),sestrin, decorin, and secreted protein acidic and rich in cysteine (SPARC), butincreased secretion of myostatin (34).According to recent research, myokines may serve as diagnostic biomarkers andtherapeutic targets in sarcopenia and sarcopenic obesity. The gene discussed is BDNF; the disease is sarcopenia.