Copper/zinc superoxide dismutase (SOD‐1) activity in regular trisomy 21, trisomy 21 by translocation and mosaic trisomy 21

Cu/Zn superoxide dismutase (SOD‐1) (E.C.1.15.1.1.) activity was estimated in children with regular trisomy 21‐Down syndrome as well as in cases of translocation and mosaic trisomy 21, as identified by the GTG, CBG and RHG banding techniques. SOD‐1 activity was found to be increased in all examined cases except trisomy 21 mosaicism. These findings provide further proof of the gene dosage theory and additional biochemical evidence for the triplicate existence of the SOD‐1 gene localized on chromosome 21