Chromodomain-helicase-DNA-binding protein 2 is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
that in humans is encoded by the ''CHD2''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Function
The
CHD family of proteins is characterized by the presence of
chromo (chromatin organization modifier) domains and
SNF2-related helicase/
ATPase
ATPases (, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, ATP hydrolase, complex V (mitochondrial electron transport), (Ca2+ + Mg2+)-ATPase, HCO3−-ATPase, adenosine triphosphatase) are ...
domains. CHD genes alter gene expression possibly by modification of
chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in r ...
structure thus altering access of the transcriptional apparatus to its chromosomal DNA template. CHD2 catalyzes the assembly of
chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in r ...
into periodic arrays; and the N-terminal region of CHD2, which contains tandem chromodomains, serves an auto-inhibitory role in both the DNA-binding and ATPase activities of CHD2.
Alternatively spliced
Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be in ...
transcript variants encoding distinct
isoforms
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some isof ...
have been found for this gene.
Clinical significance
De novo mutations and deletions in this gene have been associated with cases of epileptic encephalopathies.
CHD2 epilepsy is increasingly being identified as a subpopulation of
Lennox-Gastaut Syndrome.
CHD2 myoclonic encephalopathy is a condition characterized by recurrent seizures (epilepsy), abnormal brain function (encephalopathy), and intellectual disability. Epilepsy begins in childhood, typically between ages 6 months and 4 years. Each individual may experience a variety of seizure types, most commonly myoclonic seizures.
Recently, de novo mutations or deletions in CHD2 has been linked to intellectual disability and to autism. Researchers found 27 genes which abolish function of the corresponding protein — in at least two people with autism, and 6 genes are mutated in three or more people with autism. These six genes —
CHD8
Chromodomain-helicase-DNA-binding protein 8 is an enzyme that in humans is encoded by the ''CHD8'' gene.
Function
The gene CHD8 encodes the protein chromodomain helicase DNA binding protein 8, which is a chromatin regulator enzyme that is esse ...
,
DYRK1A
Dual specificity tyrosine-phosphorylation-regulated kinase 1A is an enzyme that in humans is encoded by the ''DYRK1A'' gene. Alternative splicing of this gene generates several transcript variants differing from each other either in the 5' UTR or ...
,
ANK2
Ankyrin-2, also known as Ankyrin-B, and Brain ankyrin, is a protein which in humans is encoded by the ''ANK2'' gene. Ankyrin-2 is ubiquitously expressed, but shows high expression in cardiac muscle. Ankyrin-2 plays an essential role in the localiz ...
,
GRIN2B
Glutamate MDAreceptor subunit epsilon-2, also known as ''N''-methyl D-aspartate receptor subtype 2B (NMDAR2B or NR2B), is a protein that in humans is encoded by the ''GRIN2B'' gene.
NMDA receptors
''N''-methyl-D-aspartate (NMDA) receptors are a ...
,
DSCAM and CHD2 — are the strongest autism candidates identified so far.
Family support
Syndromes associated with mutations or deletions in CHD2 can be devastating. Families of individuals with CHD2 mutations or deletions can join the CHD2 research and support group on Facebook or find information and support through the non-profit organization Coalition to Cure CHD2.
References
Further reading
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External links
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* {{UCSC gene info, CHD2