Lesch–Nyhan disease (LND) is an ultra-rare X-linked inborn error of metabolism caused by complete or partial deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT), a key enzyme in the purine salvage pathway. This defect leads to uric acid overproduction and a broad spectrum of neurological and behavioral manifestations, whose severity depends on the degree of residual enzymatic activity. Although emerging evidence implicates HPRT deficiency in widespread cellular dysfunctions, particularly within midbrain dopaminergic neurons, the molecular mechanisms underlying the neurobehavioral phenotype of HPRT deficiency remain poorly understood and are not adequately explained by purine metabolism dysfunctions alone. Although proteomics represents a powerful approach for elucidating molecular alterations underlying disease, it has so far found only limited application in LND research. To address this gap, we provide here the first proteomic study combined with clinical biochemistry data and pro-inflammatory cytokines profiling of plasma samples from 29 HPRT deficient individuals (21 with classic LND and 8 with Lesch–Nyhan variants – LNV). We suggest that plasma proteomics might be a potential tool in LND for monitoring disease progression and therapeutic response, potentially paving the way for targeted treatment strategies that extend beyond the purine salvage pathway to address the currently unmet clinical needs of LND patients. Graphical Abstract

Indigenous Saccharomyces cerevisiae strains persist within individual cellars and contribute to the character of spontaneously fermented wines, yet the molecular basis of their oenological differences remains largely unknown. In this work, eight predominant strains isolated from spontaneous fermentations in four Tuscan wineries were characterized by technological traits of oenological relevance and laboratory-scale fermentations of both a synthetic must and Sangiovese grape must. In each must, the strains reached similar final ethanol concentrations, although lag phase and maximum fermentation rate differed significantly, whereas the resulting wines differed significantly in glycerol, acetic acid and phenolic alcohol content and in the scores assigned by a trained sensory panel. Four strains spanning the observed range of behaviors were hence analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-ToF MS) at an early and a mid-fermentation stage, yielding 30–46 differentially abundant proteins identified per strain. Strain-specific abundance of proteins involved in glycerol formation, acetaldehyde oxidation and sulfur amino acid metabolism paralleled the corresponding differences in glycerol, acetic acid and hydrogen sulfide production, whereas glycolytic enzyme abundance varied without any corresponding variation in ethanol. Proteomic analysis thus identified candidate molecular correlates of the traits that distinguish strains, suggesting that it could complement traditional screening in the selection of indigenous starter cultures.