This spreadsheet uses the Langbehn formula to calculate conditional onset probability in Huntington’s disease, based on CAG repeat length and the knowledge that a person has remained free of motor onset to a certain age.
It can be used to calculate an individual’s probability of onset after a given number of years, or the estimated time to a given probability of onset.
It also contains the formulae in a format that allows them to be pasted into other spreadsheets, allowing calculation of these parameters for multiple individuals.
These calculations are useful for research purposes only and are essentially meaningless for real people in real life. Use of this file is granted freely but subject to agreement that it will not be used to guide clinical or personal decisions, and that the user accepts full responsibility for its use. I also make no guarantee of accuracy – you should check these calculations yourself.
Please credit me if this file has been useful, and don’t forget to cite the awesome source publication. I’m happy to offer advice about its use, subject to availability of time.