jueves, 17 de diciembre de 2015

SMARCA2 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 2 - Genetics Home Reference

SMARCA2 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 2 - Genetics Home Reference

Genetics Home Reference: your guide to understanding genetic conditions


What is the official name of the SMARCA2 gene?

The official name of this gene is “SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 2.”
SMARCA2 is the gene's official symbol. The SMARCA2 gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.

What is the normal function of the SMARCA2 gene?

The SMARCA2 gene provides instructions for making one piece (subunit) of a group of similar protein complexes known as SWI/SNF complexes. These complexes regulate gene activity (expression) by a process known as chromatin remodeling. Chromatin is the network of DNA and proteins that packages DNA into chromosomes. The structure of chromatin can be changed (remodeled) to alter how tightly DNA is packaged. Chromatin remodeling is one way gene expression is regulated during development; when DNA is tightly packed, gene expression is lower than when DNA is loosely packed. SWI/SNF complexes help with chromatin remodeling by moving parts of chromatin called nucleosomes, which makes DNA more accessible for gene expression. To provide energy for chromatin remodeling, the SMARCA2 protein uses a molecule called ATP.
SWI/SNF complexes regulate genes that are involved in many processes, including repairing damaged DNA; copying (replicating) DNA; and controlling the growth, division, and maturation (differentiation) of cells. The SMARCA2 protein and other SWI/SNF subunits are thought to act as tumor suppressors, which keep cells from growing and dividing too rapidly or in an uncontrolled way.

How are changes in the SMARCA2 gene related to health conditions?

Nicolaides-Baraitser syndrome - caused by mutations in the SMARCA2 gene
At least 50 mutations in the SMARCA2 gene have been found to cause Nicolaides-Baraitser syndrome. This condition is characterized by multiple abnormalities, primarily sparse scalp hair, small head size (microcephaly), distinctive facial features, short stature, abnormal fingers, recurrent seizures (epilepsy), and moderate to severe intellectual disability with impaired language development. Almost all SMARCA2 gene mutations that cause Nicolaides-Baraitser syndrome change single protein building blocks (amino acids) in the protein. These mutations are located within an area of the protein that attaches to ATP and is responsible for providing energy to the SWI/SNF complexes. These altered proteins are able to form SWI/SNF complexes, but these complexes are nonfunctional and cannot participate in chromatin remodeling. Disturbance of this regulatory process alters the activity of many genes, which likely explains the diverse signs and symptoms of Nicolaides-Baraitser syndrome.
cancers - associated with the SMARCA2 gene
Common DNA variants (polymorphisms) that affect the SMARCA2 gene have been found in certain types of cancer, particularly lung cancer in tobacco smokers and head and neck cancer. The changes that are associated with these cancers are described as germline, meaning that they are present from birth and found in all of the body's cells. (While the mutations that cause Nicolaides-Baraitser syndrome, which is described above, are also germline, there is no increased risk for cancer in individuals with that condition.) Two specific SMARCA2 gene polymorphisms have been found to be associated with the development of these cancers. These changes occur in an area near the SMARCA2 gene called the promoter region, which controls the production of the SMARCA2 protein. One change adds seven building blocks of DNA (nucleotides) at position -741 (insTATTTTT); the other adds six nucleotides at position -1321 (insTTTTAA) of the promoter. The incidence of lung cancer and head and neck cancer is increased only when both of these polymorphisms are present in both copies of the SMARCA2gene in each cell.
These polymorphisms impair the function of the promoter and reduce the expression of theSMARCA2 gene. The reduced gene activity likely decreases or alters protein production, which would lead to changes in SWI/SNF complexes. These changes may impair normal cell differentiation, which leads to the overgrowth of certain cell types, causing cancer. Alternatively, abnormal SWI/SNF complexes may disrupt the regulation of genes that help control the growth and division of cells, which leads to cancer. It is unclear why these changes in the promoter region of the SMARCA2 gene seem to be associated only with head and neck cancer and lung cancer in smokers.

Where is the SMARCA2 gene located?

Cytogenetic Location: 9p22.3
Molecular Location on chromosome 9: base pairs 2,015,219 to 2,193,624
(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)
The SMARCA2 gene is located on the short (p) arm of chromosome 9 at position 22.3.
The SMARCA2 gene is located on the short (p) arm of chromosome 9 at position 22.3.
More precisely, the SMARCA2 gene is located from base pair 2,015,219 to base pair 2,193,624 on chromosome 9.

Where can I find additional information about SMARCA2?

You and your healthcare professional may find the following resources about SMARCA2 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 SMARCA2 gene or gene products?

  • ATP-dependent helicase SMARCA2
  • BAF190
  • BAF190B
  • BRG1-associated factor 190B
  • BRM
  • global transcription activator homologous sequence
  • hBRM
  • hSNF2a
  • protein brahma homolog
  • SNF2
  • SNF2-alpha
  • SNF2L2
  • SNF2LA
  • SNF2/SWI2-like protein 2
  • Sth1p
  • sucrose nonfermenting 2-like protein 2
  • SWI2
  • SWI/SNF-related matrix-associated actin-dependent regulator of chromatin a2

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding SMARCA2?

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
References (6 links)

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

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