Cystinosis — a review of disease pathogenesis, management, and future treatment options

Abstract

Cystinosis is a rare autosomal recessive disease characterised by an accumulation of cystine in the lysosomes. It is caused by pathogenic variants of the cystinosin gene (CTNS), which interrupts the transport of cystine from the lysosomes into the cytosol. Intra-lysosomal cystine accumulation leads to subsequent cellular dysfunction. Cystinosis has an incidence of 0.5–1/100,000 live births. There are three forms of cystinosis: nephropathic cystinosis, juvenile cystinosis, and ocular cystinosis, with nephropathic cystinosis being the most prevalent disease subtype. Renal impairment is the most common manifestation of disease. Extrarenal manifestations of cystinosis include hypothyroidism, diabetes, and hypogonadism. The current treatment for cystinosis is cysteamine, a cystine-depleting agent. This is not a curative treatment and only aims to slow the progression of disease. A total of 90% of cystinosis patients progress to kidney failure within the first 20 years of life. Kidney transplantation is the only option available to patients once the disease has progressed to this stage. This review highlights the pathogenesis and clinical manifestations of cystinosis, as well as potential future treatment options.