Fig. 1
Urinary 1H-NMR metabolic spectrum and possible confounders. A Representation of the complete urinary 1H-NMR metabolic spectrum of a healthy individual. Exemplary metabolites and close-ups of the aromatic region as well as the creatine and creatinine peaks are shown for illustrative purposes. TSP (trimethylsilylpropionic acid-d4 sodium salt) served as reference peak. The spectral regions highlighted in green were used for further analysis. B Plotting of different SMA subgroups vs. age-matched controls revealed age as a significant confounder emphasizing the importance of age-matched experimental setups. C No differences were observed concerning gender. D Quantification of the creatine-to-creatinine quotient showed significant differences between SMA subgroups and controls. To avoid variability due to creatinine metabolism, which was recently shown to be impaired in SMA [25], the spectral regions for creatine and creatinine were excluded prior to postprocessing in the following experiments. SMA: spinal muscular atrophy. CTRL: control