SuperoxideDismutases(SODs)(E.C.1.15.1.1.)areauniquefamilyofmetalloproteinsthatcatalyzethedismutationofsuperoxideanionrADIcals(O2-)tooxygen(O2)andhydrogenperoxide(H2O2).SODisubiquitousinoxygenmetabolizingcellsprotectingthesecellsagainstdirectandindirectoxygen-mediatedfreeradicaldamage.ThehumanCu/Znsuperoxidedismutaseisadimericproteincomposedof2subunitsof153aminoacidresiduesandamolecularweightof16kDaeach.Dissociationofthesubunitsisfacilitatedbyalkylationofthetwosulfhydrylgroupsintheproteinorbyremovalofthecopperandzincions.InductionofCu/ZnSODexpressionresultinginelevatedlevelsofCu/ZnSODinhumanbodyfluidsisofdiagnosticvalueformeasuringtheactivityofdifferentdiseases.

• nephropathies:
  
  Cu/ZnSODdeterminationprovidesatoolforearlydiagnosisofnephropathies.


• monitoringoftherapeutictreatments:
  
  Cu/ZnSODisausefultherapeutictoolinthetreatmentofchronicinflammatione.g.rheumatoidarthritis(2)oroftheischemicmyocardiuminthephaseofreperfusion(6).Duetotheshorthalf-lifeofSODinjectedintothebloodcirculation,arapidassayisnecessaryformonitoringSODlevels.


• Trisomy21(Down"sSyndrome):
  
  IncaseswithDown"sSyndromeanadditionalpartofchromosome21ispresentinthegenomeofthepatientasastructuralchromosomeaberration.TheCu/ZnSODgeneislocalizedonchromosome21,closelyassociatedwiththegenecomplexresponsIBLeforthephenotypeofDown"sSyndrome.Agene-dosageeffectforCu/ZnSODinDown"sSyndromeprovidingadiagnosticMarkerforthissyndromehasbeendescribed.
  
  a)PatientswithDown"sSyndromehavesignificantlyelevatedserumandurinelevelsofCu/ZnSOD.
  
  b)PrenataldiagnosisofDown"sSyndrome:Cu/ZnSODlevelsarequantitatedfromerythrocytesoffetalumbilicalveinbloodandrelatedtothenumberofcells,thecontentofhaemoglobinandtothehaematocrit.IncaseofTrisomy21thesignificantlyelevatedlevelsofCu/ZnSODaredetermined.