title: Adenine phosphoribosyltransferase deficiency in the United Kingdom: two novel mutations and a cross-sectional survey.
abstract: BACKGROUND
  Adenine phosphoribosyltransferase deficiency is an inborn error of metabolism that can cause kidney disease from crystalline nephropathy or kidney stones.
  
  
  METHODS
  We present three cases from a single centre with varied presentations to illustrate how increasing awareness led to better patient identification. We then undertook a cross-sectional survey of all the patients identified from the Purine Research Laboratory in the UK since 1974.
  
  
  RESULTS
  Our index case presented with recurrent nephrolithiasis and was diagnosed on stone analysis, the second case presented with acute kidney injury and the third case was identified from a biopsy undertaken for acute on chronic kidney injury. Genetic studies identified two novel mutations. Twenty patients were retrospectively identified. The mean age at diagnosis was 25 years (range 2-70); eight were <20 years, seven were 20-40 years and five were >40 years. Five of the 20 patients were deceased, 3 after end-stage renal disease (ESRD). Twelve have normal renal function, one had CKD stage 3, one had severe kidney disease and one was on dialysis.
  
  
  CONCLUSIONS
  Adenine phosphoribosyltransferase deficiency presents in a wide spectrum in all age groups. Patients can be completely asymptomatic and kidney disease may be incorrectly attributed to other conditions. Outcome is poor in late diagnosis and there is a high prevalence of ESRD. Patients with unexplained renal stone disease or deterioration in kidney function should be considered for screening. Identification and surveillance of patients in the UK can improve. There is now a rare disease registry with meetings organized that include patients, families and health care providers to improve awareness.
authors.affiliation: Department of Renal Medicine, Southend University Hospital, Prittlewell Chase, Westcliff-on-Sea, Southend SO0 0RY, UK.
authors.forename: Gowrie S
authors.initials: GS
authors.lastname: Balasubramaniam
authors.affiliation: Purine Research Laboratory, St Thomas' Hospital, Westminister Bridge Road, London, UK.
authors.forename: Monica
authors.initials: M
authors.lastname: Arenas-Hernandez
authors.affiliation: Purine Research Laboratory, St Thomas' Hospital, Westminister Bridge Road, London, UK.
authors.forename: Emilia
authors.initials: E
authors.lastname: Escuredo
authors.affiliation: Purine Research Laboratory, St Thomas' Hospital, Westminister Bridge Road, London, UK.
authors.forename: Lynette
authors.initials: L
authors.lastname: Fairbanks
authors.affiliation: Purine Research Laboratory, St Thomas' Hospital, Westminister Bridge Road, London, UK.
authors.forename: Tony
authors.initials: T
authors.lastname: Marinaki
authors.affiliation: Department of Biochemistry, Southend University Hospital, Prittlewell Chase, Westcliff-on-Sea, Southend, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Mapplebeck
authors.affiliation: Department of Pathology, Barts and the London Hospital, Royal London Hospital, Whitechapel Road, Whitechapel, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Sheaff
authors.affiliation: Department of Renal Medicine, Southend University Hospital, Prittlewell Chase, Westcliff-on-Sea, Southend SO0 0RY, UK.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Almond
keywords: adenine phosphoribosyltransferase deficiency; chronic kidney disease; kidney stones; outcomes