Table 1 –

Definitions of a variety of Omes and Omics

Ome/Omic	Definition	Example Resources
Genome/genomics	The genome is the complete set of DNA in a cell. DNA carries the instructions for building all of the proteins that make each living creature unique. The human genome comprises approximately 21,000 genes. Genomics is the study of the sequence variability or gene functions within the genome, whereas genetics is the study of a particular gene.	Database of Genotypes and Phenotypes (dbGaP): www.ncbi.nlm.nih.gov/gap Cancer Genome Atlas: cancergenome.nih.gov Sequence Read Archive (SRA): www.ncbi.nlm.nih.gov/sra
Transcriptome/transcriptomics	For the instructions in DNA to be carried out, first DNA must be transcribed into corresponding molecules of RNA, referred to as transcripts. The collection of transcripts from active genes can vary among cell or tissue type and is called the transcriptome. Transcriptomics is the study of the transcriptome.	Gene Expression Omnibus: www.ncbi.nlm.gov/geo
Proteome/proteomics	The proteome consists of the collection of proteins expressed from the genes, which can vary among cell or tissue types. Proteomics is the study of the proteome.	Protein database: www.ncbi.nlm.nih.gov/protein Reactome database: www.reactome.org
Epigenome/epigenomics	Derived from the Greek, epigenome means “above the genome.” The epigenome consists of marks on the genome (e.g., methylation of the DNA) that impacts when and where a gene will be active, often in response to the endogenous and exogenous environment. The marks, which are not part of the DNA itself and can vary among cell or tissue types, can be passed on from cell to cell as cells divide and from one generation to the next. Epigenomics is the study of the epigenome.	Human Epigenome Project: www.epigenome.org
Exposome/exposomics	The exposome is the measure of all the exposures of an individual in a lifetime and how those exposures relate to health. It complements the other omics by characterizing the environment, which is important to interpreting other omics data. Exposomics is the study of the exposome.	Toxic Exposome Database: www.t3db.ca
Metabolome/metabolomics	The complete collection of all small molecules in a biological sample, which can originate from the endogenous or exogenous environment, is called the metabolome. The collection of molecules can vary among cell and tissue types. Metabolomics is the study of the metabolome.	Metabolomics Workbench: www.metabolomicsworkbench.org
Microbiome/micorbiomics	The collection of genetic material from microscopic organisms, such as bacteria, fungi, and viruses that live on and in our body, chiefly in the gut and on our skin, is called the microbiome. There are 10 times more microbial cells than human cells in a human being. Microbiomics is the study of the microbiome.	Human Microbiome Project: commonfund.nih.gov/hmp/index

“Omes” (e.g., genomes, proteomes, and microbiomes) are the objects of study, whereas “omics” (e.g., genomics, proteornics, and rnicrobiomics) are fields of study. Brief definitions of a variety of omes and omics are provided. Definitions were adapted from those provided by the National Institutes of Health National Human Genome Research Institute, the Centers for Disease Control, and omics.org.