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SLC6A19 gene

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

SLC6A19 gene

The SLC6A19 gene provides instructions for making a protein essential for transporting neutral amino acids in the intestines and kidneys.

Normal Function

The SLC6A19 gene provides instructions for making a protein called system B(0) neutral amino acid transporter 1 (B0AT1). This protein transports certain protein building blocks (amino acids), namely those with a neutral charge, into cells.

B0AT1 is found primarily in the membrane of intestinal cells that make up the brush border, which lines the walls of the intestine and absorbs nutrients from food. B0AT1 transports the neutral amino acids from food into intestinal cells; from there the amino acids are released into the bloodstream to be used by the body. B0AT1 is also found in the membrane of kidney cells, specifically in cells of the proximal tubules, which are structures that help to reabsorb nutrients and other materials into the blood and excrete unneeded substances into the urine. In the kidneys, B0AT1 reabsorbs neutral amino acids into the bloodstream so they are not released in urine.

Health Conditions Related to Genetic Changes

Hartnup disease

At least 23 mutations in the SLC6A19 gene have been found to cause Hartnup disease. This condition is characterized by increased levels of amino acids in the urine (aminoaciduria). Some individuals have episodes during which they exhibit skin rashes or movement or cognitive problems.

Most of the mutations that cause Hartnup disease change single amino acids in the B0AT1 protein, reducing its activity. A mutation that has been identified in multiple affected families replaces the amino acid aspartic acid with the amino acid asparagine at position 173 in the protein (written as Asp173Asn or D173N).

The reduced B0AT1 activity leads to large amounts of neutral amino acids being removed from the body as waste. As a result, affected individuals are lacking (deficient) in certain amino acids and vitamins. Most affected people get the nutrients they need from a well-balanced diet. However, some individuals are nutrient-deficient due to their diet, illness, stress, or a variety of other reasons and can develop skin rashes or movement or psychiatric problems. Researchers believe that many of these features are related to a deficiency of vitamin B3 (niacin) and one of its main components, the amino acid tryptophan.

Other Names for This Gene

  • B0AT1
  • HND
  • sodium-dependent amino acid transporter system B0
  • sodium-dependent neutral amino acid transporter B(0)AT1
  • solute carrier family 6 (neutral amino acid transporter), member 19
  • system B(0) neutral amino acid transporter AT1
  • system B0 neutral amino acid transporter

Frequently Asked Questions

Many individuals with Hartnup disease are asymptomatic. When symptoms occur, they often resemble pellagra, including a red, scaly rash on sun-exposed skin, neurological issues like ataxia (uncoordinated movements), tremors, and psychiatric symptoms such as anxiety or depression. Episodes can be triggered by factors like sunlight exposure, fever, stress, poor nutrition, or certain medications.
Management often involves a high-protein diet to compensate for reduced amino acid absorption, and supplementation with niacin (vitamin B3), which helps prevent pellagra-like symptoms. It's also crucial to avoid excessive sun exposure by wearing protective clothing and using sunscreen. Staying well-hydrated and avoiding prolonged fasting can also help prevent symptom exacerbation.
Hartnup disease is inherited in an autosomal recessive pattern. This means a person must inherit two copies of the mutated SLC6A19 gene (one from each parent) to develop the condition. If both parents are carriers (meaning they each have one mutated gene but do not have the disease), there is a 25% chance with each pregnancy that their child will have Hartnup disease, a 50% chance the child will be a carrier, and a 25% chance the child will not inherit any mutated genes. Genetic counseling can provide detailed risk assessments.
Diagnosis of Hartnup disease usually involves a urine test that shows elevated levels of neutral amino acids (aminoaciduria), which is characteristic of the condition. Genetic testing for mutations in the SLC6A19 gene can confirm the diagnosis. Aminoaciduria means there is an abnormally high concentration of amino acids in the urine, indicating that the kidneys are not reabsorbing these essential nutrients back into the bloodstream effectively.
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.