Gene therapy of ADA deificeincy : (i) Lymphocytes isolated form patient blood are cultured in vitro (ii) functional ADA cDNA are then indrotduced in to the cultrued lymphocytes (iii) These lympohocytes are returened back to the aptient body (iv) lymphocytes are not imortal therefore reparted infusion of gentically engineered lymphocytes is reuired (v)peanent cure introducitn of gnee isolated from bbe marow cell producing ADA in to cells at early embryonic stages