xanthinuria type II

Xanthinuria Type II Description

Xanthinuria type II, also known as XAN2, is a rare autosomal recessive disorder of purine metabolism. It is characterized by the deficiency of both molybdenum cofactor and xanthine dehydrogenase/oxidase enzyme.

• Metabolic Deficiency: The condition results from a defect in the synthesis of the molybdenum cofactor, which is essential for the proper functioning of the xanthine dehydrogenase/oxidase enzyme.
• Purine Metabolism Disorder: Xanthinuria type II affects the metabolism of purines, leading to an accumulation of xanthine in the body.

Effects on the Body

The excess xanthine can cause damage to the kidneys and other tissues. This condition is inherited in an autosomal recessive pattern, meaning that a person must inherit two copies of the mutated gene (one from each parent) to develop the disorder.

• Kidney Damage: The accumulation of xanthine can lead to kidney damage and other complications.
• Rare Condition: Xanthinuria type II is a rare condition, making it challenging to diagnose and treat.

References

• [1] Xanthinuria type II (XAN2) is an autosomal recessive inborn error of metabolism resulting from a defect in the synthesis of the molybdenum cofactor. [4]
• Type II xanthinuria, a type of classical xanthinuria, is a rare autosomal recessive disorder of purine metabolism characterized by the deficiency of both. [2]
• A rare purine metabolism disorder due to inherited deficiency of the xanthine dehydrogenase/oxidase enzyme and is characterized by very low (or undetectable) levels of molybdenum cofactor. [8]

Common Signs and Symptoms of Xanthinuria Type II

Xanthinuria type II, also known as classical hereditary xanthinuria, is a rare genetic disorder characterized by the inability to break down xanthine, a compound found in the body. This condition can lead to various signs and symptoms, which are discussed below:

• Urinary Tract Infections (UTIs): Approximately 50% of patients with classical hereditary xanthinuria experience symptoms of UTIs, including pain while urinating, frequent urination, and blood in the urine (hematuria) [4].
• Blood in Urine (Hematuria): Hematuria is a common symptom of xanthinuria type II, indicating that there are xanthine crystals present in the urine [2][6].
• Abdominal Pain: Abdominal pain and recurrent urinary tract infections can also occur due to the presence of calculi (stones) in the kidneys [1][6].
• Kidney Stones (Nephrolithiasis): The accumulation of xanthine crystals in the kidneys can lead to the formation of stones, which can impair kidney function and cause pain [6].
• Other Less Common Manifestations: In some cases, patients may experience arthropathy (joint problems), myopathy (muscle weakness), duodenal ulcers, severe metabolic acidosis, or even intracranial hemorrhage [3][5][8].

It's essential to note that not all individuals with xanthinuria type II will exhibit these symptoms. Some patients may remain asymptomatic, while others may experience a combination of the above-mentioned signs and symptoms.

References: [1] - Context result 6 [2] - Context result 9 [3] - Context result 8 [4] - Context result 4 [5] - Context result 5 [6] - Context result 6 [7] - Context result 1 [8] - Context result 8

Diagnostic Tests for Xanthinuria Type II

Xanthinuria type II, a rare autosomal recessive disorder of purine metabolism, can be diagnosed through various tests. Here are some of the diagnostic tests used to identify this condition:

• Urine Test: A urine test is commonly used to check for elevated levels of xanthine and hypoxanthine in individuals suspected of having xanthinuria type II [4]. This test helps determine if the individual has a deficiency in both xanthine oxidase (XO) and aldehyde oxidase (AO), which are enzymes that play a crucial role in purine metabolism.
• Allopurinol Loading Test: The allopurinol loading test is traditionally used to differentiate between HX types I and II [3]. This test involves administering allopurinol, a medication that inhibits XO activity, and measuring the levels of oxipurinol (a metabolite of allopurinol) in the urine. If the individual has xanthinuria type II, they will have elevated levels of oxipurinol.
• Genetic Testing: Genetic testing can also be used to diagnose xanthinuria type II [5]. This involves analyzing the genes responsible for encoding XO and AO enzymes to identify any mutations that may lead to a deficiency in these enzymes.

References

[3] Mraz, M. (2015). Modern diagnostic approach to hereditary xanthinuria. Cited by 50.

[4] Available from: [1]

[5] Genetic Testing Registry: Xanthinuria type II. Dec 1, 2015.

Note: The references provided are based on the search results and may not be an exhaustive list of all relevant studies or resources.

Treatment Options for Xanthinuria Type II

Xanthinuria type II, also known as classical xanthinuria, is a rare autosomal recessive disorder of purine metabolism characterized by the deficiency of both xanthine dehydrogenase and molybdenum cofactor sulfurase enzymes. While there are no specific therapies available for this condition, some general measures can be taken to manage its symptoms.

• Low Purine Diet: A low purine diet is often recommended to help reduce the accumulation of xanthine in the body. This involves limiting or avoiding foods that are high in purines, such as organ meats, seafood, and certain vegetables.
• High Fluid Intake: Drinking plenty of fluids can also be beneficial in helping to dissolve and eliminate excess xanthine from the body.

However, it's worth noting that these measures are not specific treatments for xanthinuria type II. The only recommended treatment for patients with this condition is a low purine diet and high intake of fluids [3].

In terms of drug treatment, there is limited information available on the use of medications specifically for xanthinuria type II. However, some studies have suggested that allopurinol, a medication used to block xanthine dehydrogenase and prevent uric acid overproduction, may be beneficial in managing this condition [2].

It's essential to consult with a qualified specialist or healthcare provider for personalized advice on managing xanthinuria type II. They can help determine the best course of treatment based on individual needs and circumstances.

References: [1] Dec 30, 2020 — No specific therapies are available for classic xanthinuria; however, some general measures are recommended as follows: High fluid intake: A ... [2] Dec 30, 2020 — Allopurinol is administered to block xanthine dehydrogenase and prevent uric acid overproduction, which leads to the accumulation of xanthine. [3] by F Grases · 2018 · Cited by 12 — The only recommended treatment for patients with xanthinuria is a low purine diet and high intake of fluids. Because the solubility of xanthine is relatively ...

Differential Diagnosis of Xanthinuria Type II

Xanthinuria type II, also known as classical xanthinuria type II, is a rare autosomal recessive disorder of purine metabolism. The differential diagnosis for this condition involves distinguishing it from other similar conditions that may present with similar symptoms.

• Allopurinol loading test: One way to diagnose xanthinuria type II is through an allopurinol loading test. This test determines if the drug allopurinol is oxidized by AOX1 to oxipurinol, which can help confirm the diagnosis of xanthinuria type II [9].
• Purine metabolic investigation: A detailed purine metabolic investigation may also be conducted to confirm the diagnosis of xanthinuria type II. This involves analyzing the levels of uric acid and other purines in the blood and urine [1].

Key differences from other conditions

Xanthinuria type II can be distinguished from other conditions that may present with similar symptoms, such as:

• Allopurinol sensitivity: Individuals with xanthinuria type II may not respond to allopurinol treatment, which can help differentiate it from other conditions [9].
• Purine metabolic profile: A detailed purine metabolic investigation can help identify the specific defect in purine metabolism that is characteristic of xanthinuria type II [1].

References

[1] Diagnosis is based on estimation of uric acid in blood and urine. If hypouricemia is confirmed, detailed purine metabolic investigation follows, and includes ... [9] The differential diagnosis for classical type II xanthinuria is an allopurinol loading test to determine if the drug is oxidized by AOX1 to oxipurinol (Ichida ...).