CSF IL-8 concentration, when measured at the time of the initial diagnostic workup, has reportedly been significantly increased in GBS when compared with CIDP, suggesting that a measurement of IL-8 with a cutoff of >70 pg/mL yields a positive predictive value of 96% to differentiate patients with GBS from those with CIDP [52]. The gene discussed is CXCL8; the disease is Guillain-Barre syndrome.