Oxidative stress in Portuguese children with Down syndrome.

BACKGROUND Individuals with Down syndrome have an accelerated process of ageing which is thought to be associated with oxidative stress. AIM Since Zn/Cu superoxide dismutase is increased by about 50% in children with Down syndrome, glutathione and other less known antioxidant mechanisms were studied to determine whether there were changes in reactive oxygen species. METHODS Plasma reduced and oxidised glutathione and red blood cells enzymes including acid phosphatase, methemoglobin reductase and transmembrane reductase were evaluated in Portuguese children with Down syndrome and their siblings, who were used as a control group. RESULTS No significant differences were found between the study and control groups. A negative correlation was noted between total glutathione and acid phosphatase in the siblings without Down syndrome, but not in the children with Down syndrome. CONCLUSION Although it is claimed that the production of hydrogen peroxide is enhanced in children with Down syndrome, their antioxidant mechanisms do not seem to be significantly different compared with their siblings. This may result in an excess of reactive oxygen species that could help to explain accelerated ageing in children with Down syndrome. Further studies will be needed to shed light on these mechanisms.