Blood-based biomarkers that were significantly increased in patients with peripheral neuropathy compared with control participants included NFL (SMD, 0.93 [95% CI, 0.82 to 1.05]; P < .001; I2 = 0%) (Figure 2), neurofilament heavy chain (SMD, 0.41 [95% CI, 0.15 to 0.67]; P = .002; I2 = 54%), and transmembrane protease serine 5 (SMD, 1.68 [95% CI, 1.43 to 1.93]; P = .001; I2 = 0%), with between-study heterogeneity ranging from not important to moderate (Figure 3). Here, TMPRSS5 is linked to peripheral neuropathy.