In a crude analysis, serum B2M levels were higher in participants with sarcopenia, weak grip strength, slow gait speed, prolonged chair stand test time, low SPPB total score and poor physical performance (p = 0.023 to < 0.001), although there was no significant difference of serum B2M between those with and without low muscle mass (Figure 6a). The gene discussed is B2M; the disease is sarcopenia.