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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


The information on this page was automatically extracted from online scientific databases.

What is the official name of the CRYBB2 gene?

The official name of this gene is “crystallin, beta B2.”

CRYBB2 is the gene's official symbol. The CRYBB2 gene is also known by other names, listed below.

What is the normal function of the CRYBB2 gene?

From NCBI Gene (

Crystallins are separated into two classes: taxon-specific, or enzyme, and ubiquitous. The latter class constitutes the major proteins of vertebrate eye lens and maintains the transparency and refractive index of the lens. Since lens central fiber cells lose their nuclei during development, these crystallins are made and then retained throughout life, making them extremely stable proteins. Mammalian lens crystallins are divided into alpha, beta, and gamma families; beta and gamma crystallins are also considered as a superfamily. Alpha and beta families are further divided into acidic and basic groups. Seven protein regions exist in crystallins: four homologous motifs, a connecting peptide, and N- and C-terminal extensions. Beta-crystallins, the most heterogeneous, differ by the presence of the C-terminal extension (present in the basic group, none in the acidic group). Beta-crystallins form aggregates of different sizes and are able to self-associate to form dimers or to form heterodimers with other beta-crystallins. This gene, a beta basic group member, is part of a gene cluster with beta-A4, beta-B1, and beta-B3. A chain-terminating mutation was found to cause type 2 cerulean cataracts. [provided by RefSeq, Jul 2008]

From UniProt (

Crystallins are the dominant structural components of the vertebrate eye lens.

How are changes in the CRYBB2 gene related to health conditions?

UniProt ( provides the following information about the CRYBB2 gene's known or predicted involvement in human disease.

Cataract 3, multiple types (CTRCT3): An opacification of the crystalline lens of the eye that frequently results in visual impairment or blindness. Opacities vary in morphology, are often confined to a portion of the lens, and may be static or progressive. CTRCT3 includes congenital cerulean and sutural cataract with punctate and cerulean opacities, among others. Cerulean cataract is characterized by peripheral bluish and white opacifications organized in concentric layers with occasional central lesions arranged radially. The opacities are observed in the superficial layers of the fetal nucleus as well as the adult nucleus of the lens. Involvement is usually bilateral. Visual acuity is only mildly reduced in childhood. In adulthood, the opacifications may progress, making lens extraction necessary. Histologically the lesions are described as fusiform cavities between lens fibers which contain a deeply staining granular material. Although the lesions may take on various colors, a dull blue is the most common appearance and is responsible for the designation cerulean cataract. Sutural cataract with punctate and cerulean opacities is characterized by white opacification around the anterior and posterior Y sutures, and grayish and bluish, spindle shaped, oval punctate and cerulean opacities of various sizes arranged in lamellar form. The spots are more concentrated towards the peripheral layers and do not delineate the embryonal or fetal nucleus. Phenotypic variation with respect to the size and density of the sutural opacities as well as the number and position of punctate and cerulean spots is observed among affected subjects. The disease is caused by mutations affecting the gene represented in this entry.

NCBI Gene ( lists the following diseases or traits (phenotypes) known or believed to be associated with changes in the CRYBB2 gene.
  • Cataract 3 (, a catalog designed for genetics professionals and researchers, provides the following information about the CRYBB2 gene and its association with health conditions.

Where is the CRYBB2 gene located?

Cytogenetic Location: 22q11.23

Molecular Location on chromosome 22: base pairs 25,212,827 to 25,231,868

The CRYBB2 gene is located on the long (q) arm of chromosome 22 at position 11.23.

The CRYBB2 gene is located on the long (q) arm of chromosome 22 at position 11.23.

More precisely, the CRYBB2 gene is located from base pair 25,212,827 to base pair 25,231,868 on chromosome 22.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about CRYBB2?

You and your healthcare professional may find the following resources about CRYBB2 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the CRYBB2 gene or gene products?

  • CCA2
  • CRYB2
  • CRYB2A
  • CTRCT3
  • D22S665

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding CRYBB2?

anterior ; bilateral ; cataract ; class ; congenital ; enzyme ; gene ; morphology ; mutation ; nucleus ; peptide ; peripheral ; posterior ; protein ; visual acuity

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Published: December 16, 2014