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Reference.org
Hypervariable region
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<p> A hypervariable region (HVR) is a location within a sequence where <a href="/facts/Polymorphism_(biology)/lf32kgfV">polymorphisms</a> frequently occur. It is used in two contexts: </p> <ul><li>In the case of nucleic acids, an HVR is where <a href="/facts/Base_pair/xmPpPQ9W">base pairs</a> frequently change. This can be due to a change in the number of repeats (which is seen in eukaryotic <a href="/facts/Nuclear_DNA/5wzCJQlb">nuclear DNA</a>) or simply low selective pressure allowing a great number of substitutions and indels (as in the case of <a href="/facts/Mitochondrial_DNA/goC0ex0X">mitochondrial DNA</a> <a href="/facts/D-loop/4yt3q9n9">D-loop</a> and 16S rRNA).</li> <li>In the case of antibodies, an HVR is where most of the differences among antibodies occur. This region is also called the <a href="/facts/Complementarity-determining_region/7vQrl1MW">complementarity-determining region</a>.</li></ul> <p>Because there already is a separate article for the antibody region, this article will focus on the nucleic acid case. </p>