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 1.247744 -0.55621185  0.4408920  0.42459559 -0.06974521
## ENSMUSG00000000003 1.497222  0.97550437  4.5068271 -2.86596635 -2.87579933
## ENSMUSG00000000028 1.294696 -0.01566068  0.1184678  0.03410627 -0.01652968
## ENSMUSG00000000037 1.015887 -5.17374634 15.3327487 -8.05074296 -2.17326840
## ENSMUSG00000000049 1.022185 -0.14994702  0.1258588  0.10717922  0.09677429
##                     Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001  5.558307 14.186320 3.163354 1.714499
## ENSMUSG00000000003 24.172354  8.325426 5.890633 9.361806
## ENSMUSG00000000028  7.742754  7.597192 3.477485 2.310449
## ENSMUSG00000000037  8.399742 13.263543 8.821118 2.381865
## ENSMUSG00000000049  6.051868  8.289543 3.177404 1.287998

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 
##        0.069857734        0.036176230        0.012853305        0.008392260 
## ENSMUSG00000000028 
##        0.005127856

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)$mist_pars, n = 3)
##                      Beta_0       Beta_1     Beta_2      Beta_3      Beta_4
## ENSMUSG00000000001 1.238881 -0.812006739 0.58507949  0.56058502 -0.03838835
## ENSMUSG00000000003 1.580430  1.471180653 2.62491775 -1.97977662 -2.39063563
## ENSMUSG00000000028 1.294058 -0.002085751 0.09029263  0.02822138 -0.01091758
##                     Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001  5.559921 12.970724 3.020887 1.767316
## ENSMUSG00000000003 25.384368  4.568840 5.218424 8.873856
## ENSMUSG00000000028  8.130446  7.802975 3.136585 2.333930
head(rowData(Dat_sce_g2)$mist_pars, n = 3)
##                        Beta_0     Beta_1    Beta_2    Beta_3    Beta_4 Sigma2_1
## ENSMUSG00000000001  1.9072704  -0.559547  3.955544  -2.15724 -1.384450 5.604358
## ENSMUSG00000000003 -0.8314969  -1.753746  4.948880  -1.62998 -1.563977 7.304354
## ENSMUSG00000000028  2.3172556 -10.503731 49.781084 -69.34902 30.284748 9.928704
##                    Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001 6.167275 3.004716 1.374840
## ENSMUSG00000000003 8.948249 4.122950 3.341158
## ENSMUSG00000000028 5.202400 4.136011 3.751942

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 ENSMUSG00000000028 ENSMUSG00000000001 
##        0.054309643        0.031626641        0.028384590        0.026200395 
## ENSMUSG00000000049 
##        0.009942994

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-3.23-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_1.34.0
##  [3] SummarizedExperiment_1.42.0 Biobase_2.72.0             
##  [5] GenomicRanges_1.64.0        Seqinfo_1.2.0              
##  [7] IRanges_2.46.0              S4Vectors_0.50.0           
##  [9] BiocGenerics_0.58.0         generics_0.1.4             
## [11] MatrixGenerics_1.24.0       matrixStats_1.5.0          
## [13] mist_1.4.0                  BiocStyle_2.40.0           
## 
## loaded via a namespace (and not attached):
##  [1] tidyselect_1.2.1         dplyr_1.2.1              farver_2.1.2            
##  [4] Biostrings_2.80.0        S7_0.2.2                 bitops_1.0-9            
##  [7] fastmap_1.2.0            RCurl_1.98-1.18          GenomicAlignments_1.48.0
## [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_1.72.0       knitr_1.51              
## [22] labeling_0.4.3           S4Arrays_1.12.0          curl_7.1.0              
## [25] DelayedArray_0.38.0      RColorBrewer_1.1-3       abind_1.4-8             
## [28] BiocParallel_1.46.0      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_0.52.0           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_1.22.0           
## [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_2.28.0         cigarillo_1.2.0         
## [73] bslib_0.10.0             MatrixModels_0.5-4       Rcpp_1.1.1-1.1          
## [76] coda_0.19-4.1            SparseArray_1.12.0       xfun_0.57               
## [79] pkgconfig_2.0.3