Contextualised urinary biomarker analysis facilitates diagnosis of paediatric obstructive sleep apnoea.

BACKGROUND: Intrinsic variance of the urine proteome limits the discriminative power of proteomic analysis and complicates potential biomarker detection in the context of paediatric sleep disorders. METHODS AND
RESULTS: Using a rigorous workflow for proteomic analysis of urine, we demonstrate that gender and diurnal effects constitute two important sources of variability in healthy children. In the context of disease, complex pathophysiological perturbations magnify these proteomic differences and therefore require contextualised biomarker analysis. Indeed, by performing biomarker discovery in a gender- and diurnal-dependent manner, we identified ∼30-fold more candidate biomarkers of paediatric obstructive sleep apnoea (OSA), a highly prevalent condition in children characterised by repetitive episodes of intermittent hypoxia and hypercapnia, and sleep fragmentation in the context of recurrent upper airway obstructive events during sleep. Remarkably, biomarkers were highly specific for gender and sampling time as poor overlap (∼3%) was observed in the proteins identified in boys and girls across morning and bedtime samples.
CONCLUSIONS: As no clinical basis to explain gender-specific effects in OSA or healthy children is apparent, we propose that implementation of contextualised biomarker strategies will be applicable to a broad range of human diseases, and may be specifically applicable to paediatric OSA.