Allelic exclusion

<p>Allelic exclusion is a process by which only one <a href="/facts/Allele/8FxCS9KA">allele</a> of a <a href="/facts/Gene/e1swwPY6">gene</a> is expressed while the other allele is silenced. This phenomenon is most notable for playing a role in the development of <a href="/facts/B_cell/6Y1tgwwp">B lymphocytes</a>, where allelic exclusion allows for each mature B lymphocyte to express only one type of <a href="/facts/Antibody/MX8pdTdP">immunoglobulin</a>. This subsequently results in each B lymphocyte being able to recognize only one antigen. This is significant as the co-expression of both alleles in B lymphocytes is associated with <a href="/facts/Autoimmunity/5cASmcfI">autoimmunity</a> and the production of <a href="/facts/Autoantibody/gkMT0XyQ">autoantibodies</a>.
</p><p>Many regulatory processes can lead to allelic exclusion. In one instance, one allele of the gene can become transcriptionally silent, resulting in the transcription and expression of only the other allele. This could be caused in part by decreased <a href="/facts/Methylation/EvDMWVW5">methylation</a> of the expressed allele. Conversely, allelic exclusion can also be regulated through asynchronous <a href="/facts/V(D)J_recombination/UpKylxB1">allelic rearrangement</a>. In this case, both alleles are transcribed but only one becomes a functional protein.
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Allelic exclusion open-in-new

Allelic exclusion