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Adenine phosphoribosyltransferase deficiency
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Adenine phosphoribosyltransferase deficiency

Adenine phosphoribosyltransferase (APRT) deficiency is an inherited condition affecting the kidneys and urinary tract, primarily characterized by the development of recurrent kidney and urinary tract stones.

Overview

Adenine phosphoribosyltransferase (APRT) deficiency is an inherited disorder that impacts the renal system. The most common feature of this condition is the formation of recurrent kidney stones, alongside frequent urinary tract stones. These stones can create blockages in the urinary tract, resulting in pain during urination and difficulty releasing urine.

The signs and symptoms of this condition can manifest at any age, from infancy to late adulthood. In infants, the first sign is typically the presence of tiny, reddish-brown grains in the diaper, which are caused by passing stones. In mid- to late childhood, recurrent stones can begin to impair kidney function. Approximately 50 percent of affected individuals do not experience symptoms until adulthood, where kidney stones and related urinary issues are typically the first signs. Other symptoms associated with these stones include fever, urinary tract infections, blood in the urine (hematuria), abdominal cramps, nausea, and vomiting.

Without appropriate treatment, kidney function can progressively decline, potentially leading to end-stage renal disease (ESRD). ESRD is a life-threatening state where the kidneys can no longer effectively filter waste from the body. The severity of APRT deficiency varies widely, even among members of the same family, and an estimated 15 to 20 percent of affected individuals never develop any signs or symptoms.

Symptoms

The symptoms of APRT deficiency are primarily related to the formation of kidney and urinary tract stones and can include:

  • Recurrent kidney and urinary tract stones
  • Pain during urination and difficulty releasing urine
  • Reddish-brown, sand-like grains in infant diapers
  • Blood in the urine (hematuria)
  • Fever
  • Urinary tract infections
  • Abdominal cramps
  • Nausea and vomiting
  • Decline in kidney function, potentially progressing to end-stage renal disease (ESRD)

Frequency

APRT deficiency is estimated to affect 1 in 27,000 people in Japan. It is less common in Europe, where the estimated prevalence is 1 in 50,000 to 100,000 individuals. The prevalence of this condition in other populations worldwide remains unknown.

Causes

APRT deficiency is caused by mutations in the APRT gene. This gene is responsible for producing the APRT enzyme, which helps convert adenine (a DNA building block or nucleotide) into adenosine monophosphate (AMP) when cells require it for energy.

Mutations in the APRT gene result in either an abnormal enzyme with reduced function or a complete lack of enzyme production. This deficiency prevents the normal conversion of adenine to AMP. Consequently, excess adenine is converted into a molecule called 2,8-dihydroxyadenine (2,8-DHA). This molecule crystallizes in the urine, forming brownish stones in the kidneys and urinary tract. Because 2,8-DHA is toxic to the kidneys, its accumulation can lead to kidney damage and the eventual development of ESRD.

Inheritance

This condition is inherited in an autosomal recessive pattern. This means that an affected individual has mutations in both copies of the gene in each cell. The parents of an individual with an autosomal recessive condition typically carry one copy of the mutated gene but do not show signs or symptoms of the disorder.

Other Names for This Condition

  • 2,8-dihydroxyadenine urolithiasis
  • 2,8-dihydroxyadeninuria
  • APRT deficiency
  • DHA crystalline nephropathy

Frequently Asked Questions

Limit intake of purine‑rich foods such as organ meats, anchovies, and certain legumes. Increase fluid intake to achieve at least 2.5–3 liters of water per day, aiming for urine volume >1.5 liters. Avoid high‑fructose corn syrup and sugary drinks, as they can increase urinary uric acid and promote stone formation. A dietitian can tailor a low‑purine plan that still meets growth and energy needs.
Baseline tests include serum creatinine, estimated GFR, and urinalysis. After diagnosis, repeat these tests every 3–6 months to detect early decline. Imaging—ultrasound or CT—should be performed annually or sooner if symptoms worsen, to assess stone burden and renal scarring. Prompt intervention for new stones can prevent irreversible kidney damage.
PRT deficiency stones are typically small, reddish‑brown, and appear in the early morning or during diaper changes in infants. A definitive test is a urine analysis for 2,8‑dihydroxyadenine crystals, which are characteristic of APRT deficiency. A urine 2,8‑dihydroxyadenine/uric acid ratio >1.0 and a positive APRT enzyme activity assay confirm the diagnosis.
llopurinol or febuxostat, which lower uric acid production, are commonly used to reduce stone formation. In addition, some clinicians prescribe a low‑dose aspirin or a specific APRT inhibitor (if available) to prevent 2,8‑dihydroxyadenine crystallization. Regular monitoring of serum uric acid and renal function is required to adjust dosing and avoid side effects.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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