Serum dipeptidyl peptidase-IV: A better screening test for early detection of mucopolysaccharidosis?

• It is aimed to investigate and compare the diagnostic utilities of some molecules.
• Urinary GAG/Cre and serum DPP-IV activity were higher in MPS patients than controls.
• There was a positive correlation between serum DPP-IV activity and urinary GAG/Cre.
• Serum DPP-IV activity can be used complementary to urinary GAG/Cre for MPS screening.

We aimed to investigate the diagnostic utility of serum DPP-IV enzyme activity, urinary GAG/Cre ratio, chitotriosidase activity, total adenosine deaminase (ADA) and ADA-1 isoenzyme activity in the diagnosis of MPS.31 MPS patients which were previously diagnosed by clinical and enzymatic analysis and 31 healthy controls matched with age and gender were included in this study.Serum DPP-IV enzyme activity, urinary GAG/Cre ratio, total ADA and ADA-1 isoenzyme activity were significantly higher in patients than in controls (p < 0.001, p < 0.001, p = 0.038 and p = 0.006, respectively). There were significant correlations between serum DPP-IV enzyme activity and urinary GAG/Cre ratios, ADA-1 activity, ADA-1/total ADA (r = 0.498, p < 0.001; r = 0.348, p = 0.006; r = 0.270, p = 0.034, respectively). Area under ROC curve for DPP-IV enzyme activity was 0.988, p < 0.001 and for urinary GAG/Cre ratio was 0.986, p < 0.001. DPP-IV enzyme activity and urinary GAG/Cre ratio were the most significant parameters according to the univariate logistic regression analysis (p = 0.001 and p < 0.001, respectively).The measurement of serum DPP-IV enzyme activity can be used complementary to the urinary GAG/Cre ratio for first-line MPS screening, since it is more less prone to age and hydration related interferences.