APRT deficiency

APRT Deficiency APRT deficiency, also known as adenine phosphoribosyltransferase deficiency, is a rare genetic disorder that affects the body's ability to process adenine, a component of DNA and RNA. This condition can lead to the accumulation of 2,8-dihydroxyadenine (DHA) in the urine, which can cause kidney stones and renal failure.

Pathophysiology

APRT deficiency is caused by mutations in the APRT gene, which provides instructions for making the enzyme adenine phosphoribosyltransferase. This enzyme is responsible for converting adenine into adenosine monophosphate (AMP) through the purine salvage pathway. When APRT is deficient, adenine is instead converted into DHA, which is poorly soluble and can precipitate in the kidneys.

Clinical Presentation

Patients with APRT deficiency may present with symptoms such as:

• Recurrent kidney stones
• Hematuria (blood in urine)
• Urinary tract infections
• Renal colic (pain due to kidney stones)
• Progressive renal failure

Diagnosis

The diagnosis of APRT deficiency can be confirmed through:

• Genetic testing to identify mutations in the APRT gene
• Urinalysis to detect the presence of DHA crystals
• Enzyme activity assays to measure APRT activity in red blood cells

Treatment

Management of APRT deficiency involves:

• Maintaining high fluid intake to prevent stone formation
• Alkalinizing the urine to increase DHA solubility
• Allopurinol therapy to reduce DHA production

Genetics

APRT deficiency is inherited in an autosomal recessive manner. This means that an individual must inherit two copies of the mutated gene, one from each parent, to be affected by the disorder.

Epidemiology

APRT deficiency is a rare condition, with a higher prevalence in certain populations, such as the Japanese and Icelandic populations. The exact prevalence is unknown, but it is considered to be underdiagnosed due to its nonspecific symptoms.

See Also

• Purine metabolism disorders
• Kidney stone disease
• Genetic testing

External Links

• National Organization for Rare Disorders (NORD) - APRT Deficiency
• Genetics Home Reference - APRT Deficiency

NIH genetic and rare disease info

• NIH info on APRT deficiency

APRT deficiency is a rare disease.