What's nephropathic cystinosis?
Nephropathic cystinosis is an autosomal recessive lysosomal storage disorder caused by variants in the CTNS gene, which encodes cystinosin, the lysosomal cystine transporter. Without working cystinosin, the amino acid cystine accumulates and crystallizes inside lysosomes throughout the body, causing progressive multi-organ damage. The infantile (nephropathic) form typically presents in the first year with renal Fanconi syndrome and, untreated, progresses to kidney failure; corneal cystine crystals and later endocrine, muscle, and other effects follow. The renal Fanconi syndrome of cystinosis is a proximal-tubule problem and is unrelated to Fanconi anemia, a separate bone-marrow disorder that shares only the name.
| Also indexed as | OMIM:219800, MONDO:0100151 |
|---|---|
| Features mapped | 14 |
| Treatments mapped | 3 |
| Published sources | 13 |
| Last reviewed | 2026-08-04 |
Signs and symptoms
Short stature
Short stature and impaired growth are common, driven by the renal losses and the body-wide effects of the disease.
Growth delay
Slowed growth, sometimes called growth retardation, is one of the body-wide effects of cystinosis, alongside eye changes, an enlarged liver, an underactive thyroid, and muscle weakness.
Primary hypothyroidism
Cystine accumulation can affect the thyroid, leading to hypothyroidism, which is checked for and treated as part of routine follow-up.
Photophobia
As corneal crystals build up, many people develop photophobia (painful sensitivity to light) and, later, visual impairment.
Corneal crystals
Cystine crystals deposit throughout the cornea from infancy. They are a characteristic finding of cystinosis and accumulate rapidly during childhood.
Visual impairment
In the eyes, cystinosis first shows up as cystine crystals in the cornea that cause no symptoms. Later it can cause photophobia and serious visual impairment.
Renal Fanconi syndrome
Renal Fanconi syndrome is usually the first sign of nephropathic cystinosis. The kidney's proximal tubules leak salts, water, minerals, and nutrients, causing excessive urination, dehydration, electrolyte loss, and poor growth.
Male infertility
Male infertility, often from azoospermia, is a recognized later complication in men with cystinosis, even when testosterone is normal.
Stage 5 chronic kidney disease
Over time, untreated or under-treated disease progresses to chronic kidney disease and eventually kidney failure (end-stage renal disease), which may require dialysis or a transplant.
Renal insufficiency
Nephropathic cystinosis usually appears in infancy with renal Fanconi syndrome. Without treatment, kidney function declines into chronic kidney disease and eventually end-stage kidney failure.
Myopathy
Later in cystinosis, cystine deposits in muscle can cause progressive muscle weakness (myopathy), which may affect the hands, swallowing, and breathing muscles over time.
Hepatomegaly
As cystine accumulates in the liver over time, the liver can become enlarged (hepatomegaly). This is one of the systemic effects of cystinosis that can appear as the disease progresses beyond the kidneys and eyes.
Elevated intracellular cystine
In cystinosis the CTNS gene defect stops cystine from leaving the lysosome, so cystine builds up to high levels inside cells throughout the body. This intracellular accumulation crystallizes and progressively damages the kidneys, eyes, and other organs.
Elevated leukocyte cystine
The key test that confirms cystinosis is measuring the cystine level inside white blood cells (leukocytes), which is markedly elevated. This leukocyte cystine measurement is also used to monitor how well cysteamine treatment is working.
How it is diagnosed
Cystinosis, nephropathic
Diagnosed using: leukocyte cystine measurement.
“Diagnosis relies on clinical evaluation, corneal examination, leukocyte cystine quantification, and CTNS genetic testing.”
Cystinosis, nephropathic
Diagnosed using: CTNS gene testing.
“Diagnosis relies on clinical evaluation, corneal examination, leukocyte cystine quantification, and CTNS genetic testing.”
Cystinosis, nephropathic
Diagnosed using: slit-lamp examination.
“On slit-lamp examination, characteristic crystalline deposits were observed in the corneal stroma.”
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
cysteamine
Starting cysteamine early and taking it consistently is central to managing cystinosis. It helps delay kidney failure and reduce complications outside the kidney. Cysteamine must be taken lifelong.
Used to help with: Cystinosis, nephropathic.
“Cysteamine therapy, reduces intracellular cystine levels and delays disease progression, significantly improving patient outcomes.”
topical cysteamine
Cysteamine eye drops (topical cysteamine) are the only treatment that reduces the buildup of cystine crystals in the cornea. The drops work only while they are used consistently.
Used to help with: Cystinosis, nephropathic.
“…treated with topical cysteamine ophthalmic solution 0.44%, resulting in subjective improvement in photophobia and stabilization of corneal…”
kidney transplantation
When the kidneys fail, a kidney transplant restores kidney function. The transplanted kidney does not develop the cystinosis kidney disease, but cystine still accumulates in other organs, so cysteamine and multidisciplinary care continue.
Used to help with: Cystinosis, nephropathic.
“Kidney transplantation remains a therapeutic option for end-stage renal…”
What changes how it shows up
Carrying the genetic change is not the whole story. The factors below are described in the research mapped here as changing whether, or how strongly, the condition appears. They modulate how the genotype is expressed; they do not, on their own, cause or cure it.
CTNS
Nephropathic cystinosis is caused by mutations in the CTNS gene, which carries the instructions for cystinosin, the protein that moves cystine out of the lysosome. When cystinosin does not work, cystine builds up inside the lysosome and damages organs throughout the body over time.
Described as modulating: Cystinosis, nephropathic.
“Cystinosis is a autosomal recessive lysosomal storage disorder caused by mutations in the CTNS gene, which encodes cystinosin, a cystine transporter. The defective function of cystinosin leads to cystine accumulation in the lysosome, resulting in progressive multi-organ damage.”
How to read the evidence labels
Where this comes from
This guide is built from 13 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.
Take it further
Printed, source-linked documents built from this condition's graph — ready to bring to an appointment or attach to a coverage request. Every claim carries its published source, the same as this guide.