Table 1.

Summary and key findings of DNA methylation studies in ADPKD.

Study	Sample Type	Key Findings	PKD1 Methylation	Technical Platform
Woo et al. (2014) [75]	Patient renal tissue	Gene body hypermethylation of cystogenesis-related genes, which were also downregulated in ADPKD.	Hypermethylation of the PKD1 gene body associated with a reduction in expression.	MIRA-Seq
Woo et al. (2015) [76]	Patient renal tissue	Hypermethylation of the MUPCDH promoter associated with transcriptional repression. Potential novel biomarker.	Not examined	MIRA-Seq
Bowden et al. (2018) [77]	Patient renal tissue	Global hypomethylation of the ADPKD genome. Differentially methylated loci are associated with ADPKD.	Hypermethylation within PKD1 gene body not associated with a reduction in transcription.	RRBS
Bowden et al. (2020) [80]	Patient renal tissue (individual cysts)	Methylation values in cysts reflect whole tissue RRBS data; highly variable methylation patterns in specific loci between cysts in a single patient.	Too little coverage to analyse.	RRBS
Kenter et al. (2020) [82]	iPSCs	Cells derived from patients display a methylation pattern indicative of disease-specific epigenetic memory.	No epigenetic changes to PKD-causing genes were found in iPSCs.	MeDIP-Seq
Hajirezaei et al. (2021) [78]	Patient blood	Methylation of the PKD1 promoter inversely correlates with gene expression.	Lower PKD1 promoter DNA methylation correlated with greater PKD1 gene expression in patients.	MS-HRM

Abbreviations used: MIRA-Seq: Methylated-CpG Island Recovery Assay with parallel sequencing; RRBS: Reduced Representation Bisulfite Sequencing; MeDIP-Seq: Methylated DNA Immunoprecipitation Sequencing; MS-HRM: Methylation-Sensitive High Resolution Melting.