In 1990, scientists at the national institutes of health used gene therapy to try to treat a 4-year-old girl suffering from severe combined immunodeficiency disease (scid). this genetic disease made her extremely susceptible to infections. the scientists used a virus to inject normal genes into the girl's immune system cells. the experiment was moderately successful, and the girl's health improved but only for short periods of time. if this form of gene therapy could be fine-tuned, how would it impact society? a. people would need to be genetically tested before having children together. b. many genetic diseases would be curable. c. the number of infections from genetically-engineered viruses would increase. d. most americans would no longer suffer from heart disease.