Gene : CTNS

What is Cystinosis?

Cystinosis is an inherited disorder caused by the accumulation of a compound called cystine in cells throughout the body. The extra cystine damages the cells and will often form crystals that can cause problems in tissues and organs. There are three different types of cystinosis based on the symptoms of the disease and the age of onset. The most severe type of cystinosis starts in infancy and causes people to have problems with their kidneys. These problems cause a person to grow poorly and have bone problems. The build up of cystine also causes crystals to form in a person's eye and cause eye pain and sensitivity to light. The children with this severe form will have complete kidney failure early in life and will need a kidney transplant. Individuals with the intermediate type of cystinosis have symptoms similar to the more severely affected group with onset starting around puberty. Kidney failure will typically occur in the late teens or 20s. The final type of cystinosis usually does not involve the kidneys. However, people with this least severe type of the disorder will have similar eye problems. Medication can be taken to reduce the amount of cystine buildup in the body. The drugs used to prevent the build up are taken by mouth to help with the kidney problems and in eye drops to help with the eye problems. The life expectancy of a person with cystinosis is dependent upon which type of cystinosis they are affected with and how much medical intervention they receive. Current medical intervention has increased the life expectancy for those children most severely affected from 10 years to more than 50 years of age. All three types of cystinosis are caused by pathogenic variants in the CTNS gene.

How is cystinosis inherited?

Cystinosis is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for cystinosis. However, the risk to have a child affected with cystinosis is increased. Testing of reproductive partners is recommended for carriers of cystinosis.

How common is cystinosis?

Cystinosis is a relatively rare disorder. It is estimated to affect 1 in 100,000 to 200,000 newborns. It has been found in all ethnic populations in the world.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
  • Copy number analysis: exons 4 & 9
Affected Systems





Carrier Rates
Detection Rate
Carrier Frequency
French Canadian > 90% 1 in 39
General Population > 95% 1 in 158

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