Distinct Neurodegenerative Pathways in Two NBIA Subtypes: Inflammatory Activation in C19orf12 but Not in PANK2 Mutation Carriers

Background: Biomarker analysis in neurodegeneration with brain iron accumulation (NBIA) can offer valuable insights into the disease’s pathology and natural history. Methods: Twenty-five patients with C19orf12 mutations causing mitochondrial membrane protein-associated neurodegeneration (MPAN), 12 patients with PANK2 mutations causing pantothenate kinase-associated neurodegeneration (PKAN), and 30 age- and gender-matched controls were studied. Serum levels of MMP-9, S100B, ICAM-1, E- and P-selectins, total α-synuclein, neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), Tau, ubiquitin-C-terminal hydrolase-L1 (UCH-L1), and brain-derived neurotrophic factor (BDNF) were measured. Clinical status was evaluated with dedicated rating scales. Results: Compared to the control group, MPAN patients had significantly higher serum levels of nearly all biomarkers, except BDNF. NfL, GFAP, and UCH-L1, were elevated by 5, 2, and 3.5 times, respectively. PKAN patients showed no significant differences in GFAP, UCH-L1, and S100B levels compared to controls. However, NfL and Tau levels were increased by 3 and 1.8 times, respectively. A correlation was observed between disease severity and levels of NfL, Tau, and UCH-L1 in MPAN, and GFAP, Tau, and UCH-L1 in PKAN. Conclusions: Patients with MPAN and PKAN showed increased levels of neurodegeneration biomarkers. Elevated inflammation and blood–brain barrier dysfunction biomarkers were specific to MPAN patients.