title: Xanthine dehydrogenase deficiency with novel sequence variations presenting as rheumatoid arthritis in a 78-year-old patient.
abstract: This report describes the clinical, biochemical and molecular data of a 78-year-old patient with xanthine dehydrogenase deficiency presenting as rheumatoid arthritis.
  
  
  BACKGROUND
  Xanthinuria type I is a rare disorder of purine metabolism caused by xanthine dehydrogenase (XDH) deficiency; fewer than 150 cases have been described in the literature so far.
  
  
  METHODS
  We describe the clinical history and urine and serum findings of a 78-year-old patient with isolated XDH deficiency presenting as rheumatoid arthritis. The diagnosis was confirmed by mutation analysis.
  
  
  RESULTS
  The patient suffered from arthral symptoms and nephrocalcinosis. Very low concentrations of uric acid were observed in her serum and urine. The allopurinol loading test indicated her xanthinuria to be type I. Analysis of genomic DNA revealed novel heterozygous deletion in exon 8 (g.27073delC, p.214QfsX4) and previously published heterozygous nucleotide missense transition in exon 25 (g.64772-C>T, p.T910M).
  
  
  CONCLUSIONS
  Hereditary xanthinuria is a rare disorder, but it also needs to be considered in patients not originating from Mediterranean countries or the Near or Middle East. Urate concentration in serum and urine may provide an initial indication of XDH deficiency before high-performance liquid chromatography (HPLC) analysis is performed. The key to identifying the disorder is a greater awareness of XDH deficiency amongst primary care physicians, nephrologists, and urologists, but also rheumatologists. The diagnosis and therapeutic management requires a multidisciplinary approach.
authors.affiliation: Department of Metabolic Diseases, Endocrinology and Diabetology, The Children's Memorial Health Institute, Al Dzieci Polskich 20, 04-730 Warsaw, Poland. ajurecka@gmail.com
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Jurecka
authors.forename: Blanka
authors.initials: B
authors.lastname: Stiburkova
authors.forename: Jakub
authors.initials: J
authors.lastname: Krijt
authors.forename: Wanda
authors.initials: W
authors.lastname: Gradowska
authors.forename: Anna
authors.initials: A
authors.lastname: Tylki-Szymanska
mesh_terms: D000368:Aged; D000493:Allopurinol; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000201:enzymology / Q000235:genetics*; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing / Q000379:methods; D006579:Heterozygote; D006801:Humans; D008661:Metabolism, Inborn Errors / Q000150:complications / Q000175:diagnosis / Q000201:enzymology / Q000235:genetics*; D020125:Mutation, Missense; D009397:Nephrocalcinosis / Q000201:enzymology / Q000235:genetics; D010641:Phenotype; D011237:Predictive Value of Tests; D017384:Sequence Deletion; D014527:Uric Acid / Q000097:blood / Q000652:urine; D014968:Xanthine Dehydrogenase / Q000172:deficiency* / Q000235:genetics*
chemical_list: D015415:Biomarkers; D014527:Uric Acid; D000493:Allopurinol; D014968:Xanthine Dehydrogenase