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MBBS QUESTION #10365
Question 1
Severe combined immunodeficiency (SCID) can result from deficiency of which purine metabolism enzyme, whose absence causes toxic intracellular accumulation of deoxyadenosine and deoxyATP, particularly damaging to developing lymphocytes?
  • Adenosine deaminase✔️
  • Xanthine oxidase
  • HGPRT
  • Orotate phosphoribosyltransferase
Correct Answer Explanation
Adenosine deaminase (ADA) deficiency causes toxic accumulation of deoxyadenosine metabolites, which are particularly damaging to lymphocyte precursors, producing one of the classic genetic causes of SCID — historically among the first conditions treated experimentally with gene therapy.