Table 2 Descriptions of data types and research levels

Data level/type

Type description

Genetic/epigenetic locus

 

SNP

Single nucleotide polymorphisms

Gene

Protein coding genes

Region

Genomic regions

Epigenetic site

Epigenetic modification sites in chromatin

Protein and other molecule

 

Protein

MDD related proteins

Molecule

Small molecules (such as transmitters)

Cell and molecular pathway

 

Molecular pathway

Intracellular or intercellular molecular pathway that have been recorded in GO, Biocarta, or KEGG.

Cell

Cell type such as pyramidal neuron, lymphocytes.

Neural system

 

Neurobiological system

Electroneurographic signals and comprehensive systems that usually contain multiple molecules, molecular pathways and cells (such as transmitter system).

Brain morphology and function

MDD related structural and functional brain changes.

Cognition and behavior

Cognitive impairments and cognitive characteristics of MDD patients, as well as depression/anxiety-like behaviors from animal models

Symptoms and signs

 

Symptoms

Diagnostic symptoms for MDD in DSM-IV (except cognitive impairments).

Signs

Clinical signs, such as blood pressure or heart rate.

Environment

Environmental events that are putative risk factors for MDD