MTHFR: Genetic variants, expression analysis and COMT interaction in major depressive disorder

Area of Science:

• Genetics
• Neuroscience
• Psychiatry

Background:

• Genetic variations in methylenetetrahydrofolate reductase (MTHFR) are implicated in major depressive disorder (MDD) and antidepressant response.
• Interactions between MTHFR and catechol-O-methyltransferase (COMT) genetic variations influence depression risk.

Purpose of the Study:

• To investigate the role of common MTHFR single nucleotide polymorphisms (SNPs) in MDD.
• To examine the impact of MTHFR and COMT gene interactions on MDD and treatment response.
• To integrate genetic data with transcriptional analysis.

Main Methods:

• Genotyping of MTHFR (A1298C, C677T) and COMT (Val158Met) in 613 MDD patients and 463 controls.
• Analysis of genetic data alongside transcriptional levels in peripheral blood cells (PBCs) and fibroblasts.
• Classification of MDD patients, including 389 with treatment-resistant depression (TRD).

Main Results:

• MTHFR A1298C CC homozygotes showed increased MDD risk in women, with a two-fold genetic risk.
• Epistasis between MTHFR A1298C and COMT Met carriers was associated with MDD.
• No significant association was found between the studied SNPs and antidepressant treatment response.
• Transcriptional analysis revealed a correlation between MTHFR mRNA levels in fibroblasts and COMT genotypes.
• PBCs data indicated significant environmental factor influences on MDD.

Conclusions:

• The MTHFR A1298C and COMT Val158Met variants, along with their interaction, are involved in MDD.
• Transcriptional data support COMT's role in the folate pathway, contributing to MDD's complex genetic and environmental interactions.
• Further research is needed to elucidate the precise mechanisms, as folate and homocysteine levels were not measured.