Which enzyme was targeted during the first clinical gene therapy given in $1990$ to a $4$ year old girl?

How was insulin obtained before the advent of $rDNA$ technology? What were the problems encountered?

Genetically engineered human insulin is prepared by using:

Statement-$I$: In vitro fertilisation leading to a test tube baby is a part of biotechnology.
Statement-$II$: Developing a $\text{DNA}$ vaccine is a part of biotechnology.

Which of the following is/are correct about Adenosine Deaminase $(ADA)$ deficiency?
$I$. In the absence of adenosine deaminase enzyme,purine metabolism is disturbed and $T$-lymphocytes fail to function.
$II$. $ADA$ deficiency is caused by the deletion of the gene for $ADA$.
$III$. In some cases,it can be cured by bone marrow transplantation and enzyme replacement therapy. But in both approaches,the patients are not completely cured.
$IV$. For permanent cure,genes isolated from the bone marrow cells producing $ADA$ at early embryonic stages can be a possible cure.
Which of the above statements are correct?

Which one of the following techniques does not serve the purpose of early diagnosis of a disease for its early treatment?