A case of APRT deficiency - a rare cause of nephrolithiasis and kidney failure

Abstract

BACKGROUND: Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal recessive disorder characterised by decreased/absent APRT activity, leading to the accumulation of adenine, whose metabolites precipitate in kidney tubules and form calculi leading to acute and eventually chronic kidney injury.1 Aims: To highlight the clinical and histological findings of APRT deficiency by examining a case of a 22 year old male presenting with acute kidney injury on a background of multiple episodes of nephrolithiasis. METHODS: Paraffin sections from the kidney biopsy were taken and subjected to H&E and special stains. The slides were subsequently viewed under normal light and polarised light. Immunofluorescence was also performed on a separate core. RESULTS: The examined biopsies showed extensive polarisable crystal deposition affecting many of the tubules in association with severe interstitial fibrosis, tubular atrophy and ischaemic glomeruli. Confirmatory genetic testing was performed post initial biopsy. Discussion(s): The patient was placed on lifelong 3-4 x weekly haemodialysis. This case highlights the importance of early recognition; especially given the evidence of successful treatment, particularly in early stages with xanthine oxidoreductase inhibitors such as allopurinol and febuxostat.