Saliva in Prader-Willi syndrome: Quantitative and qualitative characteristics

ObjectiveTo evaluate salivary flow rates and assess whole salivary total protein, MUC7 and cystatin in individuals with Prader-Willi syndrome (PWS) compared with healthy controls.DesignThe participants were forty-eight individuals with PWS (mean age 20.2 ± 9.5) and an age- and sex-matched control group. Flow rates of unstimulated whole saliva (UWS), stimulated whole saliva (SWS), submandibular/sublingual (SS), and parotid saliva (PS) were recorded (ml/min) and unstimulated whole saliva used for further protein analysis. Total protein concentration was determined via the bicinchoninic acid method, and MUC7 and cystatin levels via a Dot Blot.ResultsMean UWS (0.12 ± 0.11 vs. 0.32 ± 0.20, p < 0.001), SWS (0.41 ± 0.35 vs. 1.06 ± 0.63, p < 0.001) and SS (0.27 ± 0.19 vs. 0.50 ± 0.29, p < 0.001) salivary flow rates were significantly lower in PWS compared with controls. No significant difference was found in PS flow rate between the two groups. The mean total protein concentration (mg/ml) was 3.19 ± 3.04 in PWS compared with 1.32 ± 1.11 in controls (p < 0.001). Median concentration of MUC7 (mg/ml) was 1.29 (0.11-10.85) in the PWS group, and 0.39 (0.03-2.22) in the control group (p < 0.001). No significant difference was found in cystatin concentration between the groups. The output of proteins did not differ significantly between PWS and controls.ConclusionWith the exception of parotid saliva, salivary flow rates were lower among individuals with PWS than in their matched controls. Saliva protein concentrations in UWS were high compared with the healthy group, although the protein output did not differ significantly.