The CRYAB gene is located on chromosome 11q23.1, where it encodes a protein, called alpha-B-crystallin, made of 175 amino acid residues with a molecular weight of 22kDa. This protein is a member of the small heat-shock protein (sHSP) family of molecular chaperones. CRYAB is primarily found to be expressed in the lens, and it is widely expressed in several nonocular tissues, including cardiac and skeletal muscle. Alpha-B-crystallin protein might be responsible for the refractory index of the eye and for maintaining lens transparency. It might also represent a small heat shock protein with the potential to exert molecular chaperone function.

Defects in this protein are associated with myofibrillar myopathy type 2 (MFM2), cataract 16, multiple types (CTRCT16), cardiomyopathy, dilated 1II (CMD1II), and myofibrillar fatal infantile hypertonic myopathy, alpha-B crystallin-related (MFMFIH-CRYAB).

The CRYAB gene consists of three coding exons and spans approximately 15 kb in the genomic DNA. Mutations in this gene have been identified in patients with posterior congenital cataract type 2. A deletion mutation within exon 3, 450delA, which results in an aberrant protein, was found to be related to dominant posterior congenital cataract. Also a p.R120G missense mutation has been found to be associated with desmin-related myopathy.