How to Cite This Chapter: Chaudhry S, Pyne L, Rabbat C. Cystinosis. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. Accessed July 18, 2024.
Last Updated: May 6, 2022
Last Reviewed: May 6, 2022
Chapter Information

Definition, Etiology, Clinical FeaturesTop

Cystinosis is caused by mutations in the CTNS gene (found on chromosome 17), which encodes a lysosomal cystine/proton symporter termed cystinosin. In the absence of a functional cystinosin protein, cystine accumulates and crystallizes in the lysosomal lumen. Like in other tissues, cystine accumulates in the renal tubules and the interstitium, leading to tubular dysfunction and end-stage renal disease (ESRD).

Cystinosis has 3 forms:

1) The infantile form, also called nephropathic, is the most severe and presents at the age of 3 to 6 months, manifesting as Fanconi syndrome (see Proximal (Type 2) Renal Tubular Acidosis); such children develop ESRD by the age of 10 years.

2) The late-onset form, also known as juvenile, occurs usually around the age of 10 years, and the presentation as Fanconi syndrome is less common. Nephrotic range proteinuria can be a presenting feature. Patients develop ESRD around the age of 15 years.

3) The adult-onset form, which is usually a benign form of the disease, may have only ocular manifestations of photophobia or ocular discomfort.


Diagnosis is made by measuring intraleukocyte cystine content, slit-lamp examination of the eye, and/or testing for the CTNS gene sequence.


Recommended therapy following confirmation of the diagnosis is cysteamine, a chaperone protein that allows for effective excretion of cystine from the cells, preventing tissue deposition and damage. This has been shown to preserve renal function and prevent other end-organ manifestations of the disease.

Patients who undergo transplant for ESRD resulting from cystinosis, as long as they remain on cysteamine thereafter, have a very indolent course of cystinuria with no recurrence.

We would love to hear from you

Comments, mistakes, suggestions?

We use cookies to ensure you get the best browsing experience on our website. Refer to our Cookies Information and Privacy Policy for more details.