Abstract: A 40-year-old man presented with chronic kidney disease stage 5 at initial presentation, accompanied by mild proteinuria, right renal multiple calcifications, and ureteral stones, along with a positive family history of nephrolithiasis. Following renal transplantation, delayed graft function occurred. Allograft biopsy showed brownish, birefringent crystals in the tubules. Urine sediment microscopy showed yellowish-brown spherical crystals exhibiting a typical “Maltese cross” appearance under polarized light. Genetic testing confirmed a compound heterozygous mutation in the APRT gene. The final diagnosis was 2,8-dihydroxyadenine (2,8-DHA) crystalline nephropathy due to adenine phosphoribosyltransferase deficiency. Following treatment with febuxostat, serum creatinine further decreased.

Key words: 2,8-dihydroxyadenine, adenine phosphoribosyltransferasedeficiency, nephrolithiasis, kidney transplantation