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SLC7A9 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SLC7A9 gene

The SLC7A9 gene provides instructions for creating a protein complex in the kidneys that is essential for reabsorbing specific amino acids back into the bloodstream.

Normal Function

The SLC7A9 gene provides instructions for producing one subunit of a protein made primarily in the kidneys. This subunit joins with another protein subunit, produced from the SLC3A1 gene, to form a transporter protein complex. During the process of urine formation, this complex absorbs specific amino acids—cystine, ornithine, arginine, and lysine—back into the blood.

Health Conditions Related to Genetic Changes

Cystinuria

At least 95 mutations in the SLC7A9 gene have been identified as causes of cystinuria. These mutations often alter a single DNA building block or involve the insertion or deletion of nucleotides, leading to an abnormally functioning transporter protein complex.

When this complex fails to function correctly, the specified amino acids become concentrated in the urine. Cystine is the only amino acid among these that forms crystals and stones in the bladder or kidneys, which leads to the signs and symptoms of the condition.

Genomic Location

The SLC7A9 gene is found on chromosome 19.

Frequently Asked Questions

Yes, dietary changes are important. A low-sodium diet is often recommended, as high sodium intake can increase cystine excretion. While protein intake doesn't need to be severely restricted, avoiding excessive protein, especially methionine-rich foods, can be helpful. Maintaining a high fluid intake throughout the day and night is crucial to keep urine diluted.
Cystinuria is inherited in an autosomal recessive pattern. This means that an individual must inherit a mutated SLC7A9 gene from both parents to develop the condition. If both parents are carriers (meaning they each have one normal and one mutated gene but do not have symptoms), there is a 25% chance with each pregnancy that their child will have cystinuria.
The primary symptom of cystinuria is the formation of kidney stones, which can cause severe pain in the back or side, blood in the urine, frequent urinary tract infections, and difficulty urinating. These stones can develop at any age, often starting in childhood, and may recur frequently.
Management focuses on preventing stone formation. This typically involves drinking large amounts of water to dilute the urine, which helps prevent cystine from crystallizing. Medications that increase the solubility of cystine in urine, such as D-penicillamine or tiopronin, may also be prescribed. In some cases, potassium citrate is used to make the urine more alkaline.
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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