CST3 gene

The CST3 gene (CST3 stands for cystatin C) is a protein-coding gene located on chromosome 20p11.21.

The superfamily of cystatins includes proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. There are three inhibitor families in the superfamily, including the type 1 cystatins (stefins), the type 2 cystatins, and the kininogens.

The type-2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions, where they appear to exert protective functions.

The cystatin locus on chromosome 20 contains the majority of type 2 cystatin genes and pseudogenes. This gene is located in the cystatin locus and encodes the most common extracellular inhibitor of cysteine proteases, which is found in high concentrations in biological fluids and is expressed in virtually all organs of the body.

A mutation in the CST3 gene is associated with amyloid angiopathy (hereditary cerebral hemorrhage with amyloidosis, Icelandic type) (see below ACys amyloidosis) Expression of this protein in vascular smooth muscle cells is greatly reduced in both atherosclerotic and aneurysmal aortic lesions, demonstrating its role in vascular disease. In addition, this protein has been shown to have an antimicrobial function and to inhibit herpes simplex virus replication.

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3. Michno W et al (2022) Chemical traits of cerebral amyloid angiopathy in familial British-, Danish-, and non-Alzheimer's dementias. J Neurochem 163: 233-246.