The signs and symptoms of intermediate cystinosis are the same as nephropathic cystinosis, but they occur at a later age. Intermediate cystinosis typically begins to affect individuals around age twelve to fifteen. Malfunctioning kidneys and corneal crystals are the main initial features of this disorder. If intermediate cystinosis is left untreated, complete kidney failure will occur, but usually not until the late teens to mid twenties. People with non-nephropathic or ocular cystinosis do not usually experience growth impairment or kidney malfunction. The only symptom is photophobia due to cystine crystals in the cornea. Crystal morphology and identification
Cystine crystals are hexagonal in shape and are colorless. They are not found often in alkaline urine due to their high solubility. The colorless crystals can be difficult to distinguish from uric acid crystals which are also hexagonal. Under polarized examination, the crystals are birefringent with a polarization color interference. Genetics
Cystinosis occurs due to a mutation in the gene CTNS, located on chromosome 17, which codes for cystinosin, the lysosomal cystine transporter. Symptoms are first seen at about 3 to 18 months of age with profound polyuria (excessive urination), followed by poor growth, photophobia, and ultimately kidney failure by age 6 years in the nephropathic form. All forms of cystinosis (nephropathic, juvenile and ocular) are autosomal recessive, which means that the trait is located on an autosomal chromosome, and only an individual who inherits two copies of the gene – one from both parents – will have the disorder.
People with cystinosis are also often given sodium citrate to treat the blood acidosis, as well as potassium and phosphorus supplements as well as others. If the kidneys become significantly impaired or fail, then treatment must be begun to ensure continued survival, up to and including renal transplantation. See also
Hartnup disease
Cystinuria
CTNS

References
External links
Cystinosis at NLM Genetics Home Reference
GeneReviews/NCBI/NIH/UW entry on Cystinosis