Supplementary file 1_The Nodding syndrome cerebrospinal fluid proteome: a lens into neurodevelopmental failure consistent with environmentally triggered MECP2 dysregulation?.docx

IntroductionNodding Syndrome (NS) is a childhood-onset epileptic encephalopathy of unknown etiology, occurring in clustered outbreaks across East Africa. Despite extensive investigation, its molecular underpinnings remain unresolved.
MethodsWe performed an 18-plex tandem mass tag (TMT)-based quantitative proteomic analysis of immunodepleted cerebrospinal fluid (CSF) from Ugandan NS patients (n = 9) and age-comparable Ugandan Controls (n = 9). Differential protein abundance and pathway-level enrichment analyses were conducted to identify dysregulated molecular networks.
ResultsA total of 2,195 CSF proteins were quantified, of which 544 showed statistically significant differential abundance. Dysregulated pathways spanned immune signaling, proteostasis, synaptic function, metabolism, transcriptional regulation, neurovascular integrity, and tau-associated processes. Notably, the NS CSF proteomic profile showed substantial pathway-level convergence with that reported in MECP2 duplication syndrome (MDS), an X-linked neurodevelopmental disorder marked by MECP2 overexpression and systemic immune-metabolic dysfunction. Clinically, NS shares features with both MDS and its mechanistic converse, Rett syndrome, characterized by MECP2 loss-of-function.
DiscussionThese convergent molecular and clinical signatures suggest that NS may involve aberrant regulation of MECP2-associated networks. We propose a provisional model in which NS represents an environmentally induced functional phenocopy of MECP2 network dysregulation, shaped by early-life immune and epigenetic perturbations and amplified by postnatal environmental stressors. Although direct epigenetic data and detailed exposure histories are currently limited, this integrative framework provides a testable model linking proteomic alterations and clinical observations to neurodevelopmental and immune-metabolic mechanisms, offering tractable directions for future mechanistic and therapeutic inquiry.