FGF21 and Menkes disease: In contrast, pGSN did not correctly classify between MD and non-MD patients over 50 yrs old (Figure 3A), whereas FGF-21 (Figure 3B) and GDF-15 (Figure 3C) differentiated between these groups with a similar discrimination ability (Table 2, p-values after Bonferroni’s correction > 0.9).