OXIDATIVE STRESS IN PATIENTS WITH SEVERE MOTOR AND INTELLECTUAL DISABILITIES

Objectives: To determine the involvement of oxidative stress in pathogenesis in patients with severe motor and intellectual disabilities (SMID) and correlation of oxidative stress with severity of respiratory disturbance, which is one of the common complications in these patients.

Methods: We studied 15 patients with SMID aged 10–48 years and 17 normal controls aged 8–58 years. Levels of urinary oxidative stress biomarkers, 8-hydroxy-2'- deoxyguanosine (8-OHdG, a marker for oxidative DNA damage), hexanoyl-lysine adduct (HEL, an early marker for lipid oxidation) and acrolein-lysine adduct (ACR, a marker for lipid oxidation) were measured using an ELISA. We also measured urinary creatinine and each value was expressed relative to urinary creatinine to adjust for muscle mass. The severity of respiratory disturbance was scored as a respiratory disturbance score (RDS; 0–39 points).

Results: The urinary 8-OHdG/creatinine ratio was higher in SMID patients suffering from severe respiratory disturbance and it correlated well with RDS (rs=0.78, p<0.01). In contrast, regarding markers for lipid oxidation, neither the urinary HEL/creatinine ratio nor ACR/creatinine ratio was altered as compared with that in normal controls. Furthermore, there was no correlation between markers for lipid oxidation and RDS in patients with SMID.

Conclusions: Our results suggest that urinary 8-OHdG is a potentially useful biomarker for evaluating the severity of respiratory failure in patients with SMID.