SNPmanifold

SNPmanifold is a Python package that learns a representative manifold for single cells based on their SNPs (Single-Nucleotide Polymorphisms) using VAE (Variational AutoEncoder) and UMAP (Uniform Manifold Approximation and Projection). It takes AD matrix, DP matrix, and VCF (or variant_name.tsv) as inputs. You can compile them from bam file(s) either conveniently by cellSNP-lite or by your custom scripts.

SNPmanifold first performs simple filtering on AD matrix and DP matrix for high-quality cells and SNPs. It then trains VAE and UMAP to learn a representative manifold for single cells according to their allele frequency of different SNPs (AF = AD/DP). Finally, it classifies cells into clones and infer their phylogeny based on the manifold.

** Testing feature for mitochondrial data and somatic mutation

The default configuration for SNPmanifold now is SNP_VAE(SNPread = "normalized", missing_value = 0.5, UMI_correction = None), which works well for distinct single-cell germline mutations. We are now actively exploring an alternative configuration of SNP_VAE(SNPread = "unnormalized", missing_value = "neighbour", UMI_correction = None) or SNP_VAE(SNPread = "unnormalized", missing_value = "neighbour", UMI_correction = 'positive') which seems to work better in mitochondrial data and single-cell/spatial somatic mutation where coverage is imbalanced. You should try these two alternative configurations if you are exploring these types of data.

Installation

Quick install can be achieved via pip (python 3.8 needed)

# for published version
pip install -U SNPmanifold==0.0.9

# or developing version
pip install -U git+https://github.com/StatBiomed/SNPmanifold

Or set a conda environment before installing (credits to Xinyi Lin). Replace $myenv with the environment name you prefer.

conda create -n $myenv python=3.8
conda activate $myenv

pip install -U git+https://github.com/StatBiomed/SNPmanifold

Quick usage

Full documentation is at https://SNPmanifold.readthedocs.io.

Here is a quick start:

1. Import SNPmanifold and create an object of the class SNP_VAE.

from SNPmanifold import SNP_VAE

2. Run 4 methods (filtering, training, clustering, phylogeny) in order.

Each method can rerun sperately without reruning prior methods.

• The demo page and notebook SNPmanifold_demo.ipynb show a demo for quick usage of SNPmanifold on MKN45 cancer cell line using mitochondrial SNPs.

• See how to use it via the API page.

FAQ

If you have any questions regarding SNPmanifold, you can email Kevin Chung directly. u3570318@connect.hku.hk

1. How to choose the filtering criteria for high-quality cells and SNPs?

   The motivation of filtering is to reduce the amount of noisy low-quality cells and SNPs so that the resulting embedding is cleaner. Ideally the final matrix contains only tens to hundreds of high-quality SNPs.

   The general rationale is that cell_SNPread_threshold is high enough to filter cells with abnormally low sequencing depths, SNP_DPmean_threshold is high enough to filter SNPs with unreliable allele frequency due to low sequencing depths, and SNP_logit_var_threshold is high enough to filter SNPs that have meaninglessly low variance in allele frequency.

2. How to match input cells (or SNPs) before filtering and after filtering in SNPmanifold?

   You can use attribute cell_filter (or SNP_filter) where unfiltered_cellbarcode[cell_filter] = filtered_cellbarcode.

3. Where to find cell barcodes after using cellsnp-lite?

   Cell barcodes can be found in cellSNP.samples.tsv in the output folder of cellsnp-lite.

4. How to re-display figures in higher dpi?

   You can use functions filtering_summary(dpi = 300), training_summary(dpi = 300), clustering_summary(dpi = 300), phylogeny_summary(dpi = 300).

5. What to do when the embedding of SNPmanifold fails to converge during training?

   You can tune default hyperparameters of the optimizer in training(num_epoch = 2000, stepsize = 0.0001, z_dim = None, beta = 0) to fix the problem. Alternatively, you may consider setting more strigenet filtering criteria for cells and SNPs.

Citation

Chung, H., Huang, Y. SNPmanifold: detecting single-cell clonality and lineages from single-nucleotide variants using binomial variational autoencoder. Genome Biol 26, 309 (2025). https://doi.org/10.1186/s13059-025-03803-3