Purine salvage and degradation: practice question

The best answer is C, dATP. Adenosine deaminase deficiency causes adenosine and deoxyadenosine to build up, and deoxyadenosine is converted to dATP in lymphocytes.

Xanthine is an intermediate in purine breakdown after the adenosine deaminase step and is not what accumulates here.

Uric acid is lowered, not raised, in this disorder because purine breakdown is blocked upstream.

Orotic acid accumulates in pyrimidine synthesis defects such as orotic aciduria, not in adenosine deaminase deficiency.

It tests Purine salvage and degradation in Biochemistry. dATP inhibits ribonucleotide reductase, which blocks DNA synthesis and leads to severe combined immunodeficiency.

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.