Genomics Explained

What genomics means

Genomics is the study of an organism's whole genome, meaning all of its DNA, rather than one gene at a time. NHGRI describes it as identifying and characterizing all the genes and functional elements in a genome and how they interact. [1] The genome is the entire set of DNA instructions in a cell. [2] Genomics is a field of research and a set of technologies. It is not a treatment, and learning a person's genome does not by itself change their health.

Evidence label used here: established means the definition or finding is described the same way by national genome or health bodies. See How We Label Evidence in Specialty Topics for the full set.

Genetics and genomics: how they differ

NHGRI explains that genetics studies genes and how traits or conditions are passed from one generation to the next, while genomics studies all of a person's genes, including how they interact with each other and with the environment. [3] Single-gene conditions such as cystic fibrosis are classic genetics. Genomics is more often used for complex conditions, which are typically caused more by a combination of genetic and environmental factors than by individual genes. [4]

For the building blocks, read Genes, Variants and Gene Expression.

How genomes are read

MedlinePlus describes two common approaches in clinical testing. Genome sequencing checks all of a person's DNA, and exome sequencing checks only the parts of DNA that provide instructions for making proteins. [5] Clinical testing is done to find out about an inherited disorder [6] and is most often arranged through a health care provider. [7]

What genomics research has found

• People share almost all their DNA. The DNA of any two people is 99.9% identical, and the remaining difference carries variation relevant to health. [8]
• Many conditions are multifactorial. Heart disease, type 2 diabetes and obesity are influenced by many genes together with lifestyle and environmental exposures. [9]
• Genome-wide association studies (GWAS) find statistical links. A GWAS scans many people's genomes for variants that occur more often in those with a disease or trait. NHGRI stresses that GWAS inform us of correlation, not causation. [10]

What genomic knowledge is used for today

Research use is broad. NHGRI notes genomics now reaches medicine, agriculture, environmental monitoring, ancestry and forensics. [1] In health care, an established use is testing for inherited disorders [6] and, for some medicines, genetic information in drug labeling (see Pharmacogenomics). Risk scores built from many variants are a research and early-clinical tool (see Polygenic Risk Scores).

What genomics cannot tell you

• It does not give a complete picture. The US FDA says genetic health risk tests do not determine a person's overall risk of a disease because many other genetic, environmental and lifestyle factors contribute. [11]
• A finding is not a diagnosis. Confirmation by a clinical laboratory may be needed. See Genetic Test False Positives and Clinical Confirmation.
• A result is not a prescription for supplements or diets. For nutrition in particular, see Genetics as a Nutrition Input.

Related guides

Other layers of biology are described in Transcriptomics, Proteomics and Metabolomics and Multi-Omics Explained. Questions about who gets tested and how data is used are covered in Genetic Privacy and Incidental Findings.