Answer:
The first part in finding out Lucy has ADA-SCID was when I realized there was no HIV proteins in her blood, which got rid of the possibility of her having HIV. Then, I saw that she had a high number of Deoxyadenosine in her blood. This proves to me that she has ADA-SCID because when the ADA doesn't work you find excess amounts of Deoxyadenosine in the blood. This is the answer.
Step-by-step explanation: