Hyperemesis AKI Pregnancy — ESENeph MCQ

Correct answer: C — Adenine phosphoribosyltransferase deficiency causing insoluble DHA crystal deposition

The best answer is “Adenine phosphoribosyltransferase deficiency causing insoluble DHA crystal deposition”. Absent APRT prevents adenine salvage; xanthine oxidoreductase converts adenine to poorly soluble DHA, producing crystalluria, stones and tubulointerstitial injury. “Cystathionine beta-synthase deficiency causing homocystine stone formation” is less appropriate because this produces a different stone chemistry and metabolic disorder “Hypoxanthine-guanine phosphoribosyltransferase deficiency causing urate stone formation” is less appropriate because that purine-salvage defect does not produce DHA crystals “Primary hyperoxaluria causing recurrent calcium oxalate crystal deposition” is less appropriate because infrared spectroscopy has identified DHA rather than oxalate “Carbonic anhydrase deficiency causing recurrent calcium phosphate stone formation” is less appropriate because this does not generate 2,8-dihydroxyadenine

Reference: GeneReviews: adenine phosphoribosyltransferase deficiency: https://www.ncbi.nlm.nih.gov/books/NBK100238/