Crystallins are the dominant structural components of the vertebrate eye lens.
Defects in CRYBA4 are the cause of cataract zonular type 2 (CZ2) [MIM:610425]; also known as lamellar cataract 2. A form of zonular cataract. Zonular or lamellar cataracts are opacities, broad or narrow, usually consisting of powdery white dots affecting only certain layers or zones between the cortex and nucleus of an otherwise clear lens. The opacity may be so dense as to render the entire central region of the lens completely opaque, or so translucent that vision is hardly if at all impeded. Zonular cataracts generally do not involve the embryonic nucleus, though sometimes they involve the fetal nucleus. Usually sharply separated from a clear cortex outside them, they may have projections from their outer edges known as riders or spokes. Defects in CRYBA4 are a cause of microphthalmia isolated with cataract type 4 (MCOPCT4) [MIM:610426]. Microphthalmia is a clinically heterogeneous disorder of eye formation, ranging from small size of a single eye to complete bilateral absence of ocular tissues. Ocular abnormalities like opacities of the cornea and lens, scaring of the retina and choroid, cataractand other abnormalities like cataract may also be present.
Belongs to the beta/gamma-crystallin family. Contains 4 beta/gamma crystallin 'Greek key' domains.
Has a two-domain beta-structure, folded into four very similar Greek key motifs.