Publication at First Faculty of Medicine, Third Faculty of Medicine |
2008
Abstract
Female carriers of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency have somatic cell mosaicism of HPRT activity and are healthy. We report a 50-year-old woman without gout or nephrolithiasis.
She was never on allopurinol. Normal serum uric acid concentrations, increased plasma hypoxanthine, and xanthine were found.
HPRT activity in erythrocytes was surprisingly low: at 8.6 nmol h(-1) mg(-1) haemoglobin. Mutation analysis revealed a heterozygous HPRT gene mutation, c.215A>G (p.Tyr72Cys).
Assessment of X-inactivation ratio has shown that >75% of the active X-chromosome bears the mutant allele and could explain these unusual, previously undescribed findings.