# Does liftover update alleles

**URL:** <https://discuss.hail.is/t/does-liftover-update-alleles/4205>\
**Category:** Hail Query & hailctl\
**Created:** [September 19, 2025, 9:51pm UTC](https://discuss.hail.is/t/does-liftover-update-alleles/4205 "2025-09-19T21:51:19Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![hyslin](https://avatars.discourse-cdn.com/v4/letter/h/ea666f/32.png) [@hyslin](https://discuss.hail.is/u/hyslin)\
**Post date:** [September 19, 2025, 9:51pm UTC](https://discuss.hail.is/t/does-liftover-update-alleles/4205/1 "2025-09-19T21:51:19Z")

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When I applied liftover from GRCh38 to GRCh37 on my Hail table, the process was pretty fast but it didn’t seem to update the alleles. Does liftover also change the alleles? If not, what is the recommended way to update them?

```python
rg37 = hl.get_reference(‘GRCh37’)
rg38 = hl.get_reference(‘GRCh38’)
rg38.add_liftover(‘gs://hail-common/references/grch38_to_grch37.over.chain.gz’, rg37)

```

```python
qc_var_hg19 = qc_var.annotate(locus_grch37 = hl.liftover(qc_var.locus, ‘GRCh37’))

```

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<div class="post-metadata">

**Author:** ![chrisvittal](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/chrisvittal/32/327_2.png) [@chrisvittal](https://discuss.hail.is/u/chrisvittal)\
**Post date:** [October 29, 2025, 7:08pm UTC](https://discuss.hail.is/t/does-liftover-update-alleles/4205/2 "2025-10-29T19:08:16Z")

</div>

It does not, it only updates loci. There is no official recommended way to update them. You can check to see if the allele has changed strand using `hl.liftover(..., include_strand=True)`.

Our guide on how to use the liftover function is linked below:

> **[Hail | 
Genetics](https://hail.is/docs/0.2/guides/genetics.html#liftover-howto)**