Cystatin C: New Functional and Clinical Insights

Cystatin C, previously named gamma -trace, is a low -molecular-weight protein thatinhibits cysteine proteases and has been found in several human body fluids. It is encoded by the CST3 gene that is ubiquitously expressed at moderate levels. It is freely filtered at the glomerulus and almost completely reabsorbed and catabolized by tubular cells. Cystatins are involved in a number of normal and pathological conditions. They exert several immunomodulatory functions by controlling the activity of cysteine proteases . Theserum levels of cystatin C have been reported to be unaffected by age, gender, or muscle mass. Cystatin C, a reliable marker of renal function ,is not onlyassociated withrenal disease, but also linked to obesity, diabetes mellitus, metabolic syndrome, thyroid dysfunction, neurodegenerative diseases, ophthalmic diseases and tumors.