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Open Access Case report

Adenine phosphoribosyltransferase (APRT) deficiency: identification of a novel nonsense mutation

Rea Valaperta1*, Vittoria Rizzo2, Fortunata Lombardi1, Chiara Verdelli1, Marco Piccoli3, Andrea Ghiroldi3, Pasquale Creo3, Alessio Colombo4, Massimiliano Valisi4, Elisabetta Margiotta5, Rossella Panella6 and Elena Costa16

Author Affiliations

1 Research Laboratories - Molecular Biology, IRCCS Policlinico San Donato, Piazza E. Malan 2, 20097, San Donato Milanese, Milan, Italy

2 Department Molecular Medicine, Clinical Biochemistry Unit, Foundation IRCCS Policlinico San Matteo, University of Pavia, Pavia, Italy

3 Laboratory of Stem Cells for Tissue Engineering, IRCCS Policlinico San Donato, Milan, Italy

4 Service Lab, Fleming Research, Milan, Italy

5 Department of Nephrology, IRCCS Policlinico San Matteo, Pavia, Italy

6 Service of Laboratory Medicine, IRCCS Policlinico San Donato, Milan, Italy

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BMC Nephrology 2014, 15:102  doi:10.1186/1471-2369-15-102

Published: 1 July 2014

Abstract

Background

Adenine phosphoribosyltransferase deficiency (APRTD) is an under estimated genetic form of kidney stones and/or kidney failure, characterized by intratubular precipitation of 2,8-dihydroxyadenine crystals (2,8-DHA). Currently, five pathologic allelic variants have been identified as responsible of the complete inactivation of APRT protein.

Case presentation

In this study, we report a novel nonsense mutation of the APRT gene from a 47- year old Italian patient. The mutation, localized in the exon 5, leads to the replacement of a cytosine with a thymine (g.2098C > T), introducing a stop codon at amino acid position 147 (p.Gln147X).

This early termination was deleterious for the enzyme structural and functional integrity, as demonstrated by the structure analysis and the activity assay of the mutant APRT protein.

Conclusion

These data revealed that the p.Gln147X mutation in APRT gene might be a new cause of APRT disease.

Keywords:
APRT deficiency; Renal failure; Crystalline nephropathy