In the gene therapy the defectine gene is replaced by normal gene first clinical gene therapy was given for the successful treatment of

1. Adenosine Deficiency

2. Muscular dystrophy

3. SCID.

4. Rheumatoid arthritis

The first successful gene therapy on humans was performed in 1990 by researchers at the National Institutes of Health. The therapy treated a four-year-old child for adenosine deaminase (ADA) deficiency, a rare genetic disease in which children are born with severe immunodeficiency and are prone to repeated serious infections.

So the correct answer is 1.