GFAP and Wolfram syndrome: Within the Wolfram group, neither NfL nor GFAP levels changed over time, and NfL levels did not correlate reliably with any measures of clinical disease severity or neurodegeneration (<i>p</i> > 0.05 after excluding outliers).<h4>Conclusion</h4>Serum NfL elevation in Wolfram syndrome may reflect the ongoing, relatively slow neurodegeneration occurring in this disorder.