# arm-level CN status change, heterozygous or homozygous?

**URL:** <https://forum.depmap.org/t/arm-level-cn-status-change-heterozygous-or-homozygous/2246>\
**Category:** Q&A\
**Tags:** data\
**Created:** [January 28, 2023, 2:55pm UTC](https://forum.depmap.org/t/arm-level-cn-status-change-heterozygous-or-homozygous/2246 "2023-01-28T14:55:06Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![chenax23](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/chenax23/32/756_2.png) [@chenax23](https://forum.depmap.org/u/chenax23)\
**Post date:** [January 28, 2023, 2:55pm UTC](https://forum.depmap.org/t/arm-level-cn-status-change-heterozygous-or-homozygous/2246/1 "2023-01-28T14:55:06Z")

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Hi CCLE/DepMap team,

I’m interested in categorizing the status of a certain arm for all CCLE cell lines.

In the Cohen-Sharir\_Table\_S1.xlsx file, the Each chromosome arm is called as having copy gain (+1), loss (-1), or no change/no call (0). I would like to further ask if the loss is heterozygous or homozygous. Do you have any suggestions? What’s the formula to calculate from the segment data for a certain arm? Thanks a lot!

Best,  
Anlu

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**Author:** ![pmontgom](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/pmontgom/32/4_2.png) [@pmontgom](https://forum.depmap.org/u/pmontgom)\
**Post date:** [February 3, 2023, 9:21pm UTC](https://forum.depmap.org/t/arm-level-cn-status-change-heterozygous-or-homozygous/2246/2 "2023-02-03T21:21:00Z")

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Hello,

This data came from the publication [Aneuploidy renders cancer cells vulnerable to mitotic checkpoint inhibition](https://www.nature.com/articles/s41586-020-03114-6). That should cover the methodology for how this was derived.

Thanks,  
Phil