Table I.

Select examples of EWAS studies in the current literature.

Study	Year	Platform	Study Design	Number of Subjects	Sample Source	Primary Outcome or Exposure	Adjustment for Tissue Heterogeneity
Rakyan VK et al.	2011a	Infinium HumanMethylation27	Discordant twin-pair	15 monozygotic twin pairs	CD14+ monocytes	Type-1 diabetes	N/A (homogenous sample)
Marsit CJ et al.	2011	Infinium HumanMethylation27	Case-control	223 cases; 237 controls	Peripheral blood	Bladder cancer	None
Feber A et al.	2011	MeDIP-seq	Case-control	10 MPNST; 10 NF; and 6 normal Schwann cell samples	Nerve sheath tumor biopsies; non-neoplastic Schwann cell biopsies (expanded in culture)	Nerve sheath tumors	Nonea
Bell JT et al.	2012	Infinium HumanMethylation27	Twin Cohort	172 healthy female twins (monozygotic, dizygotic, singletons)	Whole blood	Aging	WBC counts (FACS)
Hasler R et al.	2012	Infinium HumanMethylation27; MeDip-chip (385k tiling array)	Discordant twin-pair	10 monozygotic twin pairs	Colon biopsy	Ulcerative colitis	None
Joubert BR et al.	2012	Infinium HumanMethylation450	Prospective cohort	1,062 newborns	Cord blood	Maternal smoking	Noneb
Shenker NS et al.	2012	Infinium HumanMethylation450	Nested case-control	374 cases; 374 controls	Peripheral blood	Colon cancer; breast cancer; smoking	None

Abbreviations:

N/A = not applicable; MPNST = malignant peripheral nerve sheath tumor; NF = neurofibroma; WBC = white blood cells; FACS = fluorescence-activated cell sorting

^aAlthough the cultured Schwann cells represent purified samples, the tumor biopsies are still prone to contamination by non-neoplastic and/or connective tissue

^b450K array was applied to a subset of isolated monocytes and neutrophils from 21 cord blood samples to evaluate differential methylation at the top 26 CpGs identified