# Obtaining gnomAD allele count data

**URL:** <https://discuss.hail.is/t/obtaining-gnomad-allele-count-data/2834>\
**Category:** Science\
**Created:** [September 14, 2022, 12:28pm UTC](https://discuss.hail.is/t/obtaining-gnomad-allele-count-data/2834 "2022-09-14T12:28:25Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Ruth\_Eberhardt](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/ruth_eberhardt/32/742_2.png) [@Ruth\_Eberhardt](https://discuss.hail.is/u/Ruth_Eberhardt)\
**Post date:** [September 14, 2022, 12:28pm UTC](https://discuss.hail.is/t/obtaining-gnomad-allele-count-data/2834/1 "2022-09-14T12:28:26Z")

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Hi  
I have downloaded the hail table gs://gcp-public-data–gnomad/release/2.1.1/liftover\_grch38/ht/exomes/gnomad.exomes.r2.1.1.sites.liftover\_grch38.ht (gnomad version 2 exomes lifted over to build 38) and I’d like to extract allele count data from this.

Using hl.eval(ht.globals.freq\_index\_dict) I can see a frozendict with several hundred different items in it. One of these is “‘gnomad’: 0”. Is the 0 the index within the freq field, and therefore mean that I should be extracting the AC from ht.freq[0]?

This is quite possibly a daft question but I do want to ensure that the AC I’m extracting is exactly what I think it is.  
If there is documentation on this that I’ve missed I’d appreciate links.

Many thanks in advance  
Ruth

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**Author:** ![tpoterba](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/tpoterba/32/61_2.png) [@tpoterba](https://discuss.hail.is/u/tpoterba)\
**Post date:** [September 14, 2022, 1:10pm UTC](https://discuss.hail.is/t/obtaining-gnomad-allele-count-data/2834/2 "2022-09-14T13:10:43Z")

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That’s my understanding, yes. The `freq` field is an array with lots of groups of summary metrics for various sample groups/exclusions. The `freq_index_dict` is the map for encoding which sample subgroup is which, and the first index `freq[0]` is all gnomAD samples.

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**Author:** ![Ruth\_Eberhardt](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/ruth_eberhardt/32/742_2.png) [@Ruth\_Eberhardt](https://discuss.hail.is/u/Ruth_Eberhardt)\
**Post date:** [September 14, 2022, 1:23pm UTC](https://discuss.hail.is/t/obtaining-gnomad-allele-count-data/2834/3 "2022-09-14T13:23:47Z")

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Thank you @tpoterba 👍