Contents

0.1 Introduction

mist (Methylation Inference for Single-cell along Trajectory) is an R package for differential methylation (DM) analysis of single-cell DNA methylation (scDNAm) data. The package employs a Bayesian approach to model methylation changes along pseudotime and estimates developmental-stage-specific biological variations. It supports both single-group and two-group analyses, enabling users to identify genomic features exhibiting temporal changes in methylation levels or different methylation patterns between groups.

This vignette demonstrates how to use mist for: 1. Single-group analysis. 2. Two-group analysis.

0.2 Installation

To install the latest version of mist, run the following commands:

if (!requireNamespace("BiocManager", quietly = TRUE)) {
    install.packages("BiocManager")
}

# Install mist from GitHub
BiocManager::install("https://github.com/dxd429/mist")

From Bioconductor:

if (!requireNamespace("BiocManager", quietly = TRUE)) {
    install.packages("BiocManager")
}
BiocManager::install("mist")

To view the package vignette in HTML format, run the following lines in R:

library(mist)
vignette("mist")

0.3 Example Workflow for Single-Group Analysis

In this section, we will estimate parameters and perform differential methylation analysis using single-group data.

1 Step 1: Load Example Data

Here we load the example data from GSE121708.

library(mist)
library(SingleCellExperiment)
# Load sample scDNAm data
Dat_sce <- readRDS(system.file("extdata", "group1_sampleData_sce.rds", package = "mist"))

2 Step 2: Estimate Parameters Using estiParam

# Estimate parameters for single-group
Dat_sce <- estiParam(
    Dat_sce = Dat_sce,
    Dat_name = "Methy_level_group1",
    ptime_name = "pseudotime"
)

# Check the output
head(rowData(Dat_sce)$mist_pars)
##                       Beta_0       Beta_1     Beta_2      Beta_3       Beta_4
## ENSMUSG00000000001 1.2676800 -0.598878847  0.5100346  0.34358245 -0.005613921
## ENSMUSG00000000003 1.6181894  1.495399767  3.0556513 -3.18590289 -1.554493079
## ENSMUSG00000000028 1.2936013 -0.008897203  0.1012861  0.04795074 -0.017341694
## ENSMUSG00000000037 0.9915283 -5.956975464 17.1808289 -9.39725965 -1.876998969
## ENSMUSG00000000049 1.0190144 -0.105142793  0.1280139  0.09604899  0.042100028
##                     Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001  6.432892 14.480615 3.268779 1.945273
## ENSMUSG00000000003 25.695878  5.750383 6.302808 9.662156
## ENSMUSG00000000028  8.407409  8.195303 2.857582 2.391422
## ENSMUSG00000000037  7.882963 14.108995 7.045180 2.233891
## ENSMUSG00000000049  5.968150  9.445924 3.136424 1.192521

3 Step 3: Perform Differential Methylation Analysis Using dmSingle

# Perform differential methylation analysis for the single-group
Dat_sce <- dmSingle(Dat_sce)

# View the top genomic features with drastic methylation changes
head(rowData(Dat_sce)$mist_int)
## ENSMUSG00000000037 ENSMUSG00000000003 ENSMUSG00000000001 ENSMUSG00000000049 
##        0.077244885        0.029381493        0.013297119        0.007622820 
## ENSMUSG00000000028 
##        0.005178364

4 Step 4: Perform Differential Methylation Analysis Using plotGene

# Produce scatterplot with fitted curve of a specific gene
library(ggplot2)
plotGene(Dat_sce = Dat_sce,
         Dat_name = "Methy_level_group1",
         ptime_name = "pseudotime", 
         gene_name = "ENSMUSG00000000037")

4.1 Example Workflow for Two-Group Analysis

In this section, we will estimate parameters and perform DM analysis using data from two phenotypic groups.

5 Step 1: Load Two-Group Data

# Load two-group scDNAm data
Dat_sce_g1 <- readRDS(system.file("extdata", "group1_sampleData_sce.rds", package = "mist"))
Dat_sce_g2 <- readRDS(system.file("extdata", "group2_sampleData_sce.rds", package = "mist"))

6 Step 2: Estimate Parameters Using estiParam

# Estimate parameters for both groups
Dat_sce_g1 <- estiParam(
     Dat_sce = Dat_sce_g1,
     Dat_name = "Methy_level_group1",
     ptime_name = "pseudotime"
 )

Dat_sce_g2 <- estiParam(
     Dat_sce = Dat_sce_g2,
     Dat_name = "Methy_level_group2",
     ptime_name = "pseudotime"
 ) 

# Check the output
head(rowData(Dat_sce_g1)$mist_pars, n = 3)
##                      Beta_0       Beta_1    Beta_2      Beta_3      Beta_4
## ENSMUSG00000000001 1.262652 -0.452434383 0.3431416  0.27430053  0.08524158
## ENSMUSG00000000003 1.674666  1.393614284 3.4069355 -3.21173312 -1.83042343
## ENSMUSG00000000028 1.298124 -0.009471835 0.1142839  0.04447859 -0.03703512
##                     Sigma2_1  Sigma2_2 Sigma2_3  Sigma2_4
## ENSMUSG00000000001  5.671606 16.180691 3.619820  1.992995
## ENSMUSG00000000003 25.697486  3.932150 5.527550 10.250138
## ENSMUSG00000000028  8.008246  8.066523 3.113934  2.268636
head(rowData(Dat_sce_g2)$mist_pars, n = 3)
##                        Beta_0    Beta_1    Beta_2      Beta_3     Beta_4
## ENSMUSG00000000001  1.9205187 -1.557707  8.648568  -7.6387291  0.3656197
## ENSMUSG00000000003 -0.8275165 -1.040965  2.865798  -0.7613642 -0.9971975
## ENSMUSG00000000028  2.3610669 -2.429621 11.186509 -14.0509483  5.4355475
##                     Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001  5.479661  6.481981 3.967230 1.557449
## ENSMUSG00000000003  6.900045 13.135785 5.203956 2.840029
## ENSMUSG00000000028 11.553943  4.913955 3.770720 3.202984

7 Step 3: Perform Differential Methylation Analysis for Two-Group Comparison Using dmTwoGroups

# Perform DM analysis to compare the two groups
dm_results <- dmTwoGroups(
     Dat_sce_g1 = Dat_sce_g1,
     Dat_sce_g2 = Dat_sce_g2
 )

# View the top genomic features with different temporal patterns between groups
head(dm_results)
## ENSMUSG00000000037 ENSMUSG00000000003 ENSMUSG00000000001 ENSMUSG00000000049 
##        0.066868571        0.027146463        0.025592710        0.008996873 
## ENSMUSG00000000028 
##        0.007147953

7.1 Conclusion

mist provides a comprehensive suite of tools for analyzing scDNAm data along pseudotime, whether you are working with a single group or comparing two phenotypic groups. With the combination of Bayesian modeling and differential methylation analysis, mist is a powerful tool for identifying significant genomic features in scDNAm data.

Session info

## R version 4.6.0 RC (2026-04-17 r89917)
## Platform: x86_64-pc-linux-gnu
## Running under: Ubuntu 24.04.4 LTS
## 
## Matrix products: default
## BLAS:   /home/biocbuild/bbs-3.24-bioc/R/lib/libRblas.so 
## LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.12.0  LAPACK version 3.12.0
## 
## locale:
##  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
##  [3] LC_TIME=en_GB              LC_COLLATE=C              
##  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
##  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
##  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
## [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
## 
## time zone: America/New_York
## tzcode source: system (glibc)
## 
## attached base packages:
## [1] stats4    stats     graphics  grDevices utils     datasets  methods  
## [8] base     
## 
## other attached packages:
##  [1] ggplot2_4.0.3               SingleCellExperiment_1.35.0
##  [3] SummarizedExperiment_1.43.0 Biobase_2.73.0             
##  [5] GenomicRanges_1.65.0        Seqinfo_1.3.0              
##  [7] IRanges_2.47.0              S4Vectors_0.51.0           
##  [9] BiocGenerics_0.59.0         generics_0.1.4             
## [11] MatrixGenerics_1.25.0       matrixStats_1.5.0          
## [13] mist_1.5.0                  BiocStyle_2.41.0           
## 
## loaded via a namespace (and not attached):
##  [1] tidyselect_1.2.1         dplyr_1.2.1              farver_2.1.2            
##  [4] Biostrings_2.81.0        S7_0.2.2                 bitops_1.0-9            
##  [7] fastmap_1.2.0            RCurl_1.98-1.18          GenomicAlignments_1.49.0
## [10] XML_3.99-0.23            digest_0.6.39            lifecycle_1.0.5         
## [13] survival_3.8-6           magrittr_2.0.5           compiler_4.6.0          
## [16] rlang_1.2.0              sass_0.4.10              tools_4.6.0             
## [19] yaml_2.3.12              rtracklayer_1.73.0       knitr_1.51              
## [22] labeling_0.4.3           S4Arrays_1.13.0          curl_7.1.0              
## [25] DelayedArray_0.39.0      RColorBrewer_1.1-3       abind_1.4-8             
## [28] BiocParallel_1.47.0      withr_3.0.2              grid_4.6.0              
## [31] scales_1.4.0             MASS_7.3-65              mcmc_0.9-8              
## [34] tinytex_0.59             dichromat_2.0-0.1        cli_3.6.6               
## [37] mvtnorm_1.3-7            rmarkdown_2.31           crayon_1.5.3            
## [40] otel_0.2.0               httr_1.4.8               rjson_0.2.23            
## [43] cachem_1.1.0             splines_4.6.0            parallel_4.6.0          
## [46] BiocManager_1.30.27      XVector_0.53.0           restfulr_0.0.16         
## [49] vctrs_0.7.3              Matrix_1.7-5             jsonlite_2.0.0          
## [52] SparseM_1.84-2           carData_3.0-6            bookdown_0.46           
## [55] car_3.1-5                MCMCpack_1.7-1           Formula_1.2-5           
## [58] magick_2.9.1             jquerylib_0.1.4          glue_1.8.1              
## [61] codetools_0.2-20         gtable_0.3.6             BiocIO_1.23.0           
## [64] tibble_3.3.1             pillar_1.11.1            htmltools_0.5.9         
## [67] quantreg_6.1             R6_2.6.1                 evaluate_1.0.5          
## [70] lattice_0.22-9           Rsamtools_2.29.0         cigarillo_1.3.0         
## [73] bslib_0.10.0             MatrixModels_0.5-4       Rcpp_1.1.1-1.1          
## [76] coda_0.19-4.1            SparseArray_1.13.0       xfun_0.57               
## [79] pkgconfig_2.0.3