Cystinosis: Symptoms, Causes, Types, and Treatment

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Quick Answer

Cystinosis is a rare, lifelong genetic condition in which cystine crystals accumulate in cells, damaging the kidneys, eyes and other organs. It is inherited when both parents pass on a mutated gene. The most common form causes kidney failure by age 10 without treatment, but daily cysteamine and eventual kidney transplant allow most people to live into adulthood.

What the research says

• Staying on cysteamine and a planned move to adult care protect the kidney graft. A 2026 scoping review confirms that cystinosis affects about 1 in 100,000 to 200,000 live births and reports that long-term kidney graft success depends on cysteamine adherence and structured multidisciplinary transition from pediatric to adult care ( (Subhash et al., BMC Nephrology, 2026) [2].

• Outcomes depend heavily on early diagnosis and on getting the right dose. A scoping review of 1,125 patients with cystinosis in Iran over 37 years found a median age at presentation of 0.73 years, at diagnosis of 1.5 years, and at end-stage kidney disease of 8.3 years; failure to thrive was the presenting problem in 94%, more than half of patients assessed were not receiving the correct cysteamine dose, and only about 8.7% reached adulthood in that setting ( (Hooman & Hosseini, Iranian Journal of Kidney Diseases, 2025) [3].

What Is Cystinosis?

Cystinosis is a rare genetic condition in which an amino acid called cystine builds up within your cells. Too much cystine damages cells by forming crystals that accumulate and cause problems in your organs and tissues. The disease most often affects the kidneys and eyes, but it can also damage the brain, muscles, liver, thyroid, pancreas, and testes.

Cystinosis is a type of lysosomal storage disorder. Lysosomes are small compartments inside cells that break down nutrients such as carbohydrates, proteins, and fats. Special transporter proteins move leftover materials, including cystine, out of the lysosomes. When this transporter is missing or defective, cystine accumulates, forms crystals, and slowly damages the cells of your organs.

The condition is rare but serious, with a lifelong impact. Prompt diagnosis and treatment can slow the progression of the disease significantly.

Cystinosis overview: how cystine crystals damage cells and which organs are affected.

Key Facts at a Glance

Fact	Detail
What it is	A rare genetic lysosomal storage disorder caused by cystine buildup in cells
Who it affects	About 1 in 100,000 to 200,000 births worldwide
Inheritance	Autosomal recessive (both parents must carry the mutated gene)
Main organs affected	Kidneys and eyes; also brain, muscles, liver, thyroid, pancreas, testes
Most common type	Nephropathic (infantile) cystinosis, about 95% of cases
Untreated outcome	Complete kidney failure by age 10 (nephropathic type)
With treatment	Life expectancy extends into adulthood; some live beyond 50
Cure	None, but lifelong medication and kidney transplant change the outlook

What Are the Three Types of Cystinosis?

There are three main types of cystinosis. They differ depending on when symptoms first appear (age of onset) and how severe they are.

Type	Also Known As	Onset	Severity	Kidney Outcome Without Treatment
Nephropathic cystinosis	Infantile / early-onset	First 6–18 months of life	Most severe; about 95% of all cases	Kidney failure by age 10
Intermediate cystinosis	Adolescent / juvenile / late-onset	Childhood or adolescence	Less severe, develops more slowly	Kidney failure by mid-teens to mid-20s
Non-nephropathic cystinosis	Benign / ocular cystinosis	Varies (often middle-aged adults)	Mildest; eyes only	No kidney damage in most cases

Nephropathic (Infantile) Cystinosis

Nephropathic cystinosis is the most common form, affecting about 95% of people with the condition, and it is also the most severe. Infants develop a type of kidney damage called renal Fanconi syndrome, in which minerals and nutrients are not absorbed into the bloodstream properly. Instead, they are lost through urine. This nutrient loss causes growth delays, soft bowed bones (rickets), and many other debilitating symptoms.

By age 2, cystine crystals may form in the corneas of a child's eyes. The buildup eventually causes extreme sensitivity to light (photophobia), which can produce intense eye pain and discomfort. Children with nephropathic cystinosis will ultimately require a kidney transplant. If left untreated, complete kidney failure occurs by age 10. Children who receive treatment can often survive at least into adulthood with a good quality of life.

Intermediate Cystinosis

Intermediate cystinosis produces the same signs and symptoms as the infantile form, but they develop later in childhood or adolescence and may be less severe and progress more slowly. People with intermediate cystinosis will eventually need a kidney transplant. If left untreated, complete kidney failure occurs by the mid-teens to mid-20s.

Non-Nephropathic (Ocular) Cystinosis

Non-nephropathic cystinosis affects the eyes only. Cystine crystals in the corneas cause light sensitivity, but most people with this type do not develop kidney damage or experience other symptoms. Because symptoms are absent or subtle, the age at diagnosis varies widely, and it usually affects middle-aged adults.

What Causes Cystinosis?

Genetic mutations in the CTNS gene cause cystinosis. The CTNS gene tells your body how to produce a protein called cystinosin. Cystinosin is a transporter protein responsible for moving the amino acid cystine out of the lysosomes, the cellular compartments that break down minerals and other nutrients.

When the CTNS gene is mutated, cystinosin is defective. Cystine cannot exit the lysosomes and begins to build up. Crystals form and accumulate, which damages the cells in your organs.

Inheritance Fact	Detail
Pattern	Autosomal recessive: both parents must pass on a mutated copy
Carrier parents	Usually show no symptoms themselves
Risk per pregnancy	1 in 4 (25%) chance if both parents are carriers
Gene involved	CTNS gene (encodes the cystinosin transporter protein)
Can it be prevented?	No, because it is a genetic condition

Cystinosis is a genetic condition that can affect anyone, regardless of background. The disease is inherited in an autosomal recessive pattern, meaning both biological parents must pass on a copy of the mutated gene. Carrier parents usually show no symptoms.

What Are the Symptoms of Cystinosis?

Cystinosis symptoms and severity vary based on the age of onset and diagnosis.

Nephropathic Cystinosis Symptoms

Symptoms typically appear between the ages of 6 and 18 months as signs of kidney damage develop. These include excessive thirst (polydipsia), excessive urination (polyuria), electrolyte imbalances, vomiting, dehydration, and fever.

Other symptoms may include rickets, growth delay or failure to thrive, scarred or cloudy corneas, light sensitivity (photophobia), vision loss, and difficulty swallowing (dysphagia).

Symptom Category	Specific Signs
Kidney-related	Excessive thirst, excessive urination, electrolyte imbalances, vomiting, dehydration, fever
Growth and bones	Rickets (soft bowed bones), growth delay, failure to thrive, short stature
Eye-related	Scarred or cloudy corneas, light sensitivity (photophobia), vision loss
Other	Difficulty swallowing (dysphagia), fatigue, muscle weakness, myopathy

Intermediate Cystinosis Symptoms

The symptoms are the same as infantile cystinosis but appear later, during childhood or adolescence, and tend to be less severe. Other common late-onset symptoms include fatigue, muscle weakness, myopathy (muscle disease), short stature, delayed puberty, and infertility.

Ocular Cystinosis Symptoms

Ocular cystinosis affects the corneas of the eyes only. Light sensitivity is typically the only sign of the condition, and no kidney-related symptoms develop.

Cystinosis symptoms by category: kidney, eye, growth and bones, and muscle.

How Is Cystinosis Diagnosed?

A healthcare provider will ask about symptoms and medical history, perform a physical exam, and request several tests to confirm the diagnosis.

Diagnostic Test	What It Checks
Blood test	Cystine levels in white blood cells
Genetic testing	Mutations in the CTNS gene
Urinalysis	Excess loss of minerals, nutrients, electrolytes, and amino acids in urine
Eye examination	Cystine crystals in the corneas, examined with a slit lamp microscope by an ophthalmologist

If you are pregnant and have a family history of cystinosis, prenatal testing may be available when both parents are confirmed carriers. Amniocentesis collects a cell sample from the amniotic fluid surrounding the developing fetus to check cystine levels. Chorionic villus sampling (CVS) examines cells found on the chorionic villi of the placenta.

What Are the Treatment Options for Cystinosis?

The first line of treatment is a medication called cysteamine, a cystine-depleting agent that works to lower cystine levels in the cells of your body.

When used early, cysteamine can slow the development and progression of kidney damage. It has significantly delayed the need for kidney transplantation, and some children have been able to delay it until adulthood. Cysteamine also improves the growth of children with the disease. It comes in two oral forms: a standard form taken about every six hours, and a delayed-release form, intended for people aged 6 and older, taken about every 12 hours.

Treatment	Purpose
Cysteamine (oral)	Lowers cystine levels; slows kidney damage; improves growth
Cysteamine eye drops	Dissolve corneal crystals and relieve light sensitivity (about every waking hour)
Fluids and electrolytes	Replace losses from Fanconi syndrome
Phosphate medications	Correct defective phosphate absorption in the kidneys
Growth hormone therapy	Address growth delay
Insulin	Treat insulin-dependent diabetes
Testosterone	Treat underactive testicular function (hypogonadism)
Speech and language therapy	Address swallowing and communication difficulties
Feeding tube	Ensure nutrition and medication delivery for feeding difficulties
Dialysis	Bridge treatment for kidney failure
Kidney transplant	Definitive treatment for kidney failure
Genetic counseling	Support for family planning decisions

Cysteamine Side Effects

The medication cysteamine smells foul and has an unpleasant taste. Some people experience nausea, vomiting, and heartburn while taking it. Cysteamine may also cause excess stomach acid production, and some people take proton pump inhibitors to reduce stomach acid and improve gastrointestinal symptoms. It may also cause bad breath (halitosis) and a bad sweat odor.

Treating Kidney Failure

Despite early diagnosis and treatment, people with nephropathic and intermediate cystinosis will eventually develop kidney failure. Providers may first treat kidney failure with dialysis, a machine that filters waste from the blood and maintains correct chemical levels. Kidney failure is not reversible, so a kidney transplant is eventually required.

Kidney transplants have worked very well for people with cystinosis. Cystine does not collect in a donated kidney. However, cystine may still build up in other organs, so lifelong medication remains necessary.

Cystinosis treatment: cysteamine, eye drops, supportive care, and kidney transplant.

What Is the Long-Term Outlook for Cystinosis?

The outlook has improved dramatically. At one point, nephropathic cystinosis was fatal in young children. Today, with cysteamine and advances in kidney transplantation, life expectancy reaches far into adulthood. Some people live beyond 50 years of age.

Scenario	Outlook
Untreated nephropathic	Kidney failure by age 10; previously fatal in young children
Treated nephropathic	Survival into adulthood with good quality of life; transplant eventually needed
Intermediate type	Kidney failure by mid-teens to mid-20s without treatment; transplant eventually needed
Ocular type	No kidney damage in most cases; light sensitivity managed with drops and sunglasses

Early diagnosis is vital: you can slow the progression of the disease with proper treatment. If you are taking cysteamine, you should continue to use it throughout your life. Research shows it can prevent many late complications of cystinosis that do not involve the kidneys.

Living With Cystinosis

Living with cystinosis means managing a chronic, lifelong condition with a team of specialists, including nephrologists, ophthalmologists, endocrinologists, genetic counselors, and other providers. Daily medication, regular monitoring, and eventual kidney transplantation are part of most treatment journeys.

For the ocular form, simple measures help: avoiding bright lights, wearing sunglasses, and keeping the eyes lubricated. In rare cases, a corneal transplant may be necessary.

Conclusion

Cystinosis is a rare but serious genetic condition caused by cystine crystal buildup in cells, most severely affecting the kidneys and eyes. While once fatal in young children, today's treatment, daily cysteamine medication combined with kidney transplantation, allows most people to live well into adulthood, with some reaching age 50 and beyond. Early diagnosis is the single most important factor in slowing the disease.

If your child shows signs of excessive thirst, frequent urination, poor growth, or light sensitivity, talk to your healthcare provider. If cystinosis runs in your family and you are planning a pregnancy, ask about genetic counseling and carrier testing.

Related reading: Kidney transplant: understanding the procedure, benefits, and recovery.

Frequently Asked Questions

What is cystinosis?

Cystinosis is a rare genetic disease in which the amino acid cystine accumulates inside cells, forming crystals that damage organs. It most often affects the kidneys and eyes, but can also involve the brain, muscles, liver, thyroid, pancreas, and testes. It is a type of lysosomal storage disorder.

Is cystinosis a form of kidney disease?

Not exactly. Cystinosis is a genetic metabolic disorder, but its most common form (nephropathic cystinosis) causes severe kidney damage called renal Fanconi syndrome, in which minerals and nutrients are lost through urine. Most patients eventually develop kidney failure requiring transplantation.

How common is cystinosis?

Cystinosis is rare. It occurs in about 1 in 100,000 to 200,000 births worldwide. The nephropathic (infantile) form accounts for about 95% of all cases.

Is cystinosis inherited?

Yes. Cystinosis is inherited in an autosomal recessive pattern. Both biological parents must pass on a copy of the mutated CTNS gene. Carrier parents usually show no symptoms. If both parents are carriers, there is a 25% (1 in 4) chance of having a child with cystinosis.

What gene causes cystinosis?

Cystinosis is caused by mutations in the CTNS gene, which encodes a transporter protein called cystinosin. Cystinosin moves cystine out of cellular lysosomes. When it is defective, cystine builds up, forms crystals, and damages cells and organs.

What are the three types of cystinosis?

The three types are nephropathic (infantile/early-onset, about 95% of cases, most severe), intermediate (adolescent/juvenile/late-onset, same symptoms but later and milder), and non-nephropathic (ocular/benign, affecting only the eyes with no kidney damage in most cases).

When do cystinosis symptoms first appear?

In the most common (nephropathic) form, symptoms typically appear between 6 and 18 months of age. Signs include excessive thirst, frequent urination, vomiting, dehydration, fever, and poor growth. In the ocular form, diagnosis often happens in middle-aged adults.

Can cystinosis be cured?

There is no cure for cystinosis. However, lifelong medication with cysteamine slows the disease and significantly delays kidney failure, and kidney transplantation is highly effective for treating kidney failure. Cystine does not collect in a donated kidney.

What is the life expectancy for cystinosis?

Life expectancy has improved dramatically. With cysteamine and kidney transplantation, most people live well into adulthood, and some live beyond 50 years. Without treatment, nephropathic cystinosis was historically fatal in young children, with kidney failure by age 10.

Can cystinosis be prevented?

No. Cystinosis is a genetic condition and cannot be prevented. However, prospective parents with a family history can undergo genetic carrier testing and counseling to understand their risk before or during pregnancy. Prenatal testing (amniocentesis or chorionic villus sampling) is also available for carrier couples.

References

1. Cleveland Clinic. Cystinosis. Cleveland Clinic. Medically reviewed; last updated January 27, 2023. https://my.clevelandclinic.org/health/diseases/24657-cystinosis

2. Subhash S, Pantelakis N, Backston K, et al. Bridging pediatric to adult care in cystinosis: a scoping review of healthcare transition of care protocols and a roadmap for future practice. BMC Nephrology. 2026;27(1). PMID 42157047. https://doi.org/10.1186/s12882-026-05061-2

3. Hooman N, Hosseini S. A report on nephropathic cystinosis in Iran: a scoping review. Iranian Journal of Kidney Diseases. 2025;19(5):260-271. PMID 42234905. https://pubmed.ncbi.nlm.nih.gov/42234905/

Medical disclaimer

This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Always seek the guidance of your healthcare professional with any questions about your or your child's health. In a medical emergency, call 911 or your local emergency number.