Contributor: Gordon K. Klintworth
Cystinosis (cystine storage disease) is a rare autosomal recessive inherited disorder in which cystine crystals accumulate within the cells. Several different types of cystinosis are recognized: infantile cystinosis [cystinosis - infantile type], childhood (nephropathic) cystinosis [cystinosis - childhood], juvenile cystinosis [cystinosis - juvenile type], and adult cystinosis [cystinosis - adult type]. At least some types are cystinosis are caused by a mutation in the CTNS gene (childhood cystinosis, ocular nonnephropathic cystinosis). In cystinosis tinsel-like, fine white crystals appear in the subepithelial conjunctival tissue. The crystals are insoluble in absolute ethanol but soluble in many other solutions. There is a widespread accumulation of cystine crystals in bone marrow, liver, spleen, lymph nodes, and kidneys. Plasma cystine and cysteine levels are not consistently elevated. Other conditions that are associated with corneal crystals need to be distinuished from cystinosis. They include monoclonal gammopathy of uncertain significance, multiple myeloma, Schnyder crystalline corneal dystrophy, infectious pseudocrystalline keratopathy. The eye is not affected in cystinuria, which it is sometimes confused, with cystinosis.