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Phosphoribosylpyrophosphate synthetase superactivity and recurrent infections is caused by a p.Val142Leu mutation in PRS‐I
Author(s) -
Moran Rocio,
Kuilenburg André B.P.,
Duley John,
Nabuurs Sander B.,
RetnoFitri Aditia,
Christodoulou John,
Roelofsen Jeroen,
Yntema Helger G.,
Friedman Neil R.,
van Bokhoven Hans,
de Brouwer Arjan P.M.
Publication year - 2012
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.34428
Subject(s) - missense mutation , overproduction , allosteric regulation , mutation , uric acid , loss function , biology , hypotonia , biochemistry , medicine , endocrinology , phenotype , chemistry , genetics , enzyme , gene
Abstract We identified a novel missense mutation, c.424G>C (p.Val142Leu) in PRPS1 in a patient with uric acid overproduction without gout but with developmental delay, hypotonia, hearing loss, and recurrent respiratory infections. The uric acid overproduction accompanying this combination of symptoms suggests that the patient presented with phosphoribosylpyrophosphate (PRPP) synthetase superactivity, but recurrent infections have not been associated with superactivity until now. However, recurrent infections are a prominent feature of patients with Arts syndrome, which is caused by PRPS1 loss‐of‐function mutations, indicating that the patient reported here has an intermediate phenotype. Molecular modeling predicts that the p.Val142Leu change affects both allosteric sites that are involved in inhibition of PRPS1 and the ATP‐binding site, which suggests that this substitution can result both in a gain‐of‐function and loss‐of‐function of PRPP synthetase. This finding is in line with the normal PRPP synthetase activity in fibroblasts and the absence of activity in erythrocytes of the present patient. We postulate that the overall effect of the p.Val142Leu change on protein activity is determined by the cell type, being a gain‐of‐function in proliferating cells and a loss‐of‐function in postmitotic cells. Our results show that missense mutations in PRPS1 can cause a continuous spectrum of features ranging from progressive non‐syndromic postlingual hearing impairment to uric acid overproduction, neuropathy, and recurrent infections depending on the functional sites that are affected. © 2012 Wiley Periodicals, Inc.