ACTN3 and sarcopenia: Amongst the genes that have been identified to play important roles in the pathogenesis of sarcopenia are hormone and receptors genes such as vitamin D receptor (VDR) and androgen receptor (AR); growth factors and cytokines genes such as ciliary neurotrophic factor (CNTF), myostatin (MSTN), and insulin-like growth factor 1 (IGF1); structural and metabolic genes such as angiotensin I converting enzyme 1 (ACE) and alpha actinin 3 (ACTN3) [21].