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Molybdenum, the XDH Gene, and How They Affect Purine Metabolism

Molybdenum is an essential trace mineral that helps several enzymes do their jobs. One of these enzymes, xanthine dehydrogenase, is made by the XDH gene and depends on molybdenum to convert purines into uric acid so the body can eliminate them. Variants in the XDH gene can reduce or remove this enzyme’s activity, which may cause xanthine to build up instead of being converted to uric acid. This can sometimes lead to very low blood uric acid levels and an increased risk of forming xanthine kidney stones.

Why this matters

  • Purines are compounds found naturally in your body and in many foods. Proper breakdown prevents buildup of intermediate products like xanthine.
  • When xanthine accumulates it may form crystals that can lead to kidney stones or other urinary tract symptoms.
  • Molybdenum is required for the enzyme to function. Diet, hydration, and genetics together influence risk.

Common signs and when to follow up

  • Many people with one altered copy of XDH (carriers) have no symptoms.
  • People with two altered copies may have very low uric acid and a higher chance of xanthine stones.
  • Consider testing urine and blood uric acid if you have recurrent kidney stones, unexplained low uric acid, or family history of xanthinuria.

Practical Recommendations

PlexusDx provides genetic education only and does not give medical advice. Always discuss test results and changes to diet, supplements, or medical care with your healthcare provider.

Hydration and lifestyle

  • Maintain good hydration: aim for urine that is light yellow most of the day. Increased fluid intake helps dilute urine and reduces stone risk.
  • Avoid prolonged dehydration, especially during exercise or heat exposure.
  • Maintain a healthy body weight and regular physical activity to support overall kidney and metabolic health.

Dietary guidance

  • Moderate intake of high-purine foods: limit organ meats (liver, kidney), certain seafood (anchovies, sardines, mackerel), and very high-purine preparations.
  • Focus on a balanced diet rich in legumes, whole grains, fruits, and vegetables. These foods support overall purine metabolism and kidney health.
  • Limit excessive protein from single sources and consider spreading protein intake across meals.
  • Avoid high-sulfite foods if you are sensitive; molybdenum-dependent enzymes also help break down sulfites.

Supplements and nutrients

  • Do not start molybdenum supplements without medical guidance. Most people get adequate molybdenum from food, and supplementation is rarely necessary.
  • Discuss multivitamins or targeted supplements with your provider if you have restricted diets or malabsorption issues.
  • Maintain adequate dietary calcium and avoid excessive vitamin C doses that may change urinary oxalate — discuss with your clinician if you have a history of stones.

When to test and what to monitor

  • Blood uric acid levels: very low levels could prompt further evaluation for xanthinuria.
  • Urine analysis for xanthine crystals and 24-hour urine collection if kidney stones are recurrent.
  • Kidney imaging if clinically indicated for stones or pain.
  • Genetic counseling if you have two copies of a pathogenic XDH variant, or family members with symptomatic xanthinuria.

Genetic Interpretations

The accordion below explains what each genotype at rs72549369 in the XDH gene typically means. These interpretations are educational only. PlexusDx does not provide medical advice. Review results with your healthcare provider for personalized guidance.

Two effect alleles (AA) — Carrier of mutation related to xanthine oxidase deficiency

If you have the AA genotype for rs72549369, you carry two copies of the effect allele associated with xanthine oxidase deficiency, also called xanthinuria. The XDH gene encodes xanthine dehydrogenase, a molybdenum-dependent enzyme that converts purines into uric acid. With both copies altered, enzyme activity may be reduced or absent.

Potential consequences

  • Xanthine can accumulate in blood and urine instead of being converted to uric acid.
  • Very low blood uric acid levels are possible.
  • Increased risk of xanthine kidney stones and related urinary symptoms.

Suggested actions

  • Discuss these results with your healthcare provider and consider referral to a specialist or genetic counselor.
  • Have blood uric acid measured and consider urine testing for xanthine if clinically indicated.
  • Prioritize hydration and dietary moderation of high-purine foods such as organ meats and certain seafood.
  • Avoid starting molybdenum supplements without clinician input.

PlexusDx does not provide medical advice. Consult your healthcare provider for evaluation, testing, and personalized recommendations.

One effect allele (AG) — Carrier with likely adequate enzyme function

If you have the AG genotype for rs72549369, you carry one copy of the effect allele and one normal copy of XDH. Most carriers have one working gene copy that produces enough xanthine dehydrogenase for normal purine breakdown. Carriers typically do not have symptoms of xanthinuria.

What to watch for

  • Enzyme activity is generally adequate but may be slightly reduced in some carriers.
  • Routine care is usually sufficient; symptomatic issues are uncommon.

Practical tips

  • Stay well-hydrated to support kidney health and reduce stone risk.
  • Consider moderating intake of high-purine foods such as organ meats and certain seafood.
  • Discuss any history of kidney stones or family concerns with your healthcare provider to determine if further testing is needed.

PlexusDx does not provide medical advice. Consult your healthcare provider for testing or if you have symptoms.

No effect alleles (GG) — Typical genotype

If you have the GG genotype for rs72549369, you carry two copies of the non-effect allele. This is the typical genotype and suggests the XDH gene at this location functions normally to produce xanthine dehydrogenase. Purine metabolism at this genetic position is expected to work as intended.

General guidance

  • Maintain normal hydration and a balanced diet rich in legumes, whole grains, fruits, and vegetables.
  • No special genetic follow-up for xanthinuria is typically required unless you have clinical symptoms or family history of kidney stones.
  • Speak with your healthcare provider about routine screening only if you experience urinary symptoms or recurrent stones.

PlexusDx does not provide medical advice. Consult your healthcare provider for any health concerns.

Final notes

Variants in the XDH gene can influence how your body handles purines and the risk of xanthine accumulation. Whether you carry two, one, or no effect alleles, lifestyle measures such as staying hydrated, moderating high-purine foods, and working with your healthcare provider on any testing are practical steps to support kidney and metabolic health. PlexusDx provides educational information only; always consult your healthcare provider for medical advice, diagnosis, or treatment based on your genetic results.