A MIR4646 associated methylation locus is hypomethylated in adolescent depression

• Background: Studies of epigenetics and transcriptional activity in adolescents may provide knowledge about possible preventive strategies of depression. Methods: We present a methylome-wide association study (MWAS) and cohort validation analysis of depression in adolescents, in two separate cohorts: discovery (n = 93) and validation data set 1 (n = 78). The genome-wide methylation pattern was measured from whole blood using the Illumina 450K array. A second validation cohort, validation data set 2, consists of post-mortem brain biopsies from depressed adults (n = 58). We performed a MWAS by robust multiple linear regressions of methylation to a modified risk-score assessment of depression. Methylation levels of candidate CpG sites were correlated with expression levels of the associated gene in an independent cohort of 11 healthy volunteers. Results: The methylation state of two CpG sites reliably predicted ratings of depression in adolescents (cg13227623 and cg04102384) (p < 10E-06). Cohort validation analysis confirmed cg04102384 - located in the promoter region of microRNA 4646 (MIR4646) - to be hypomethylated in both validation data set 1 and validation data set 2 (p < 0.05). Cg04102384 was inversely correlated to expression levels of MIR4646-3p in healthy controls (p < 0.05). Limitations: MIR4646 was not differentially expressed in a subset of samples with adolescent depression measured by qRT-PCR measurements. Conclusion: We identify a specific MIR4646 associated epigenetic risk site to be associated with depression in adolescents. Cg04102384 putatively regulates gene expression of MIR4646-3p. Target gene prediction and gene set overrepresentation analysis revealed involvement of this miRNA in fatty acid elongation, a process related to omega-3 fatty acids, previously associated with depression.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Neurologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Neurology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Psykiatri (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Psychiatry (hsv//eng)

Nyckelord

MIR4646

Methylome-wide association study

Adolescent depression

Omega-3

MicroRNA

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