Major depressive disorder may be linked to gene variant involved in brain function

Written by Roisin Conneely

Researchers in China have discovered a variant of the gene SLC6A15, which appears to affect brain function in patients with major depressive disorder (MDD).
The gene encodes a neutral amino acid transporter, distributed throughout the brain, and is thought to be involved in regulating transmission of glutamate, ultimately affecting functions such as memory and attention span.

The team examined 67 patients experiencing their first occurrence of MDD, along with 44 healthy individuals, through a combination functional MRI and genotyping techniques. Brain activity was measured according to levels of regional homogeneity and results were analyzed in order to demonstrate how genotype and disease status interact in MDD.

The researchers reported a link between genotype and fMRI results in the cingulum, corpus callosum and frontal, parietal and temporal lobes – all areas where abnormal levels of SLC6A15 were expressed. They discovered that left corpus callosum regional homogeneity was positively correlated with scores of the Hamilton Depression Score, suggesting that pathology of this region is linked to depressive disorders.

This study highlights a novel association between resting brain function and levels of SLC6A15 across numerous regions of the brain, strongly indicating a link to the pathogenesis of MDD. Combining genetic analysis with imaging studies holds potential for furthering the understanding such disorders, described as “bleeding edge neurogenetics” by Garth D. Ehrlich, editor of Genetic Testing and Molecular Biomarkers.

 Sources: Wang Lijuan, Liu Zhifen, Cao Xiaohua et al. A combined study of SLC6A15 gene polymorphism and the resting-state functional magnetic resonance imaging in first-episode drug-naive major depressive disorder. Genet. Test. Mol. Biomarkers. 21(9) 523-530 (2017); http://online.liebertpub.com/doi/full/10.1089/gtmb.2016.0426