Final answer:
The subject of this question is Medicine. It relates to a pediatric emergency involving ADA deficiency that requires a bone marrow transplant before the age of 1 to prevent death.
Step-by-step explanation:
The subject of this question is Medicine. Specifically, it deals with a pediatric emergency involving a deficiency of the enzyme ADA (adenosine deaminase) which is inherited in an autosomal recessive manner. The question mentions the urgent need for a bone marrow transplant before the age of 1 to prevent death.