What it means to have a mutation and what role mutations play in Huntington’s disease.
The Hairpin-Mediated Polymerase Slippage Model
As mentioned in Part 5, the polymerase slippage model by itself could not explain why some expansions in HD are so large (sometimes in the hundreds of codon repeats); slippage this long-range is energetically unfavorable. However, hairpins are helpful in the polymerase slippage model because they produce hydrogen bonds that would not otherwise be present, and these bonds help compensate for the energy lost due to long-range slippage. As a result, hairpins have the unique ability to minimize the energy difference between the normal double helix and the double helix where slippage has occurred. The hairpin-mediated polymerase slippage model is energy efficient and it thus provides an effective answer to the main criticism of the regular polymerase slippage model. Although the hairpin-mediated model is very enticing, more research is necessary to clearly determine just how big of a role hairpin-mediated polymerase slippage actually plays in expansion.
Last Modified: 1-28-04
An educational product of HOPES, not to be used in place of medical care. For more information about HOPES, click on the Logo.
To contact HOPES with comments or questions, click here.
