Adenine phosphoribosyltransferase deficiency (APRT Deficiency) (2 8 dihydroxyadenine urolithiasis)

What is Adenine phosphoribosyltransferase deficiency (APRT Deficiency) (2 8 dihydroxyadenine urolithiasis)

Adenine phosphoribosyltransferase deficiency is caused by homozygous or compound heterozygous mutation in the gene encoding adenine phosphoribosyltransferase on chromosome 16q24.

APRT deficiency is an autosomal recessive metabolic disorder that can lead to accumulation of the insoluble purine 2 8 dihydroxyadenine (DHA) in the kidney, which results in crystalluria and the formation of urinary stones.

Synonyms

  1. 2 8 dihydroxyadenine urolithiasis
  2. APRT Deficiency
  3. Urolithiasis , DHA
  4. Nephrolithiasis, DHA

Prevalence

1/50,000 to 1/100,000 in Caucasian

1/27,000 in Japanese

> 1/15,000 in Icelandic

Age of onset

  1. Childhood
  2. Adolescent
  3. Adult
  4. Elderly
  5. Infancy

Symptoms of APRT Deficiency

Very common symptoms

  • Abnormal enzyme/coenzyme activity

Common symptoms

  • Acute kidney injury 
  • Chronic kidney disease 
  • Dysuria 
  • Hypertension 
  • Nephrolithiasis 
  • Proteinuria 
  • Renal insufficiency

Occasional Symptoms

  • Abdominal colic 
  • Atrial fibrillation 
  • Flank pain 
  • Macroscopic hematuria 
  • Oliguria 
  • Recurrent urinary tract infections 
  • Stage 5 chronic kidney disease 
  • Uric acid nephrolithiasis 
  • Urinary hesitancy 
  • Urinary retention 

Prognosis of APRT Deficiency

Prognosis is excellent with early diagnosis which is the key

Prognosis also depends on progression of this treatable disorder.

Allopurinol therapy effectively prevents stone recurrence and can lead to an improvement or stabilization of renal function in most patients.

Stone recurrence and renal complications are rare in patients who remain compliant with allopurinol therapy.

Treatment

  1. Daily dose of Allopurinol (10mg/kg per day in children and 300 mg per day in adults)
  2. Low purine diet
  3. High intake of fluids
  4. Febuxostat, a xanthine oxydase inhibitor, is very efficacious than allopurinol in reducing DHA excretion
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