In ADA-SCID, the toxic accumulator that primarily kills lymphocytes is:

• A Deoxyguanosine triphosphate (dGTP)
• B Deoxyadenosine triphosphate (dATP) ✓
• C Uric acid
• D Adenosine monophosphate (AMP)

Explanation

ADA deficiency leads to accumulation of adenosine and deoxyadenosine. Deoxyadenosine is phosphorylated to dATP by deoxycytidine kinase (which is highly expressed in lymphocytes). Elevated dATP allosterically inhibits ribonucleotide reductase, blocking DNA synthesis and triggering apoptosis preferentially in T and B lymphocytes, causing SCID. Gene therapy targeting the ADA gene is clinically used.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.