Table 1.

Basic concepts in genomic medicine

Term	Description
Biomarker	Also called a biological marker, a classical biomarker is any characteristic that can be used to assess a particular disease state or physiological function. A genomic biomarker is “a DNA or RNA characteristic that is an indicator of normal biologic processes, pathogenic processes, and/or response to therapeutic or other intervention” [8]. A genomic biomarker reflects the expression, function, or regulation of a gene.
Codon	DNA or RNA nucleotides or bases are read in groups of three (e.g., ATG, AUG), which are called codons. Start and stop codons show when a protein sequence starts or ends.
DNA	Deoxyribonucleic acid (DNA) is the carrier of genetic information. DNA consists of four nucleotides or bases (A, T, G, and C). DNA can replicate or make copies of itself.
Exome	The approximately 1% of the genome formed only by exons.
Exon	The protein coding sequence of DNA (the part of the genome that is expressed).
Gene	A gene is a specified sequence of DNA that serves as the basic unit of heredity [9]. “Gene” comes from the Greek word genea, meaning generation.
Gene expression	When a gene is turned on and its RNA or protein product is being made, the gene is said to be expressed. The on/off state of cells is called a gene expression profile, with each cell type having a unique profile [10].
Genome	The genome includes all of an organism’s DNA, including both exons and introns.
Germline	Germline cells are sperm, egg, or embryo cells. Changes to the germline are permanent. Germline traits or mutations are inherited and generational.
Intron	The non-protein coding sequence of DNA (the part of the genome that is not expressed).
MicroRNA	MicroRNA (miRNA) is a type of genetic material that regulates gene expression. miRNAs are promising biomarkers and can point toward development of new therapeutic approaches.
RNA	Ribonucleic acid (RNA) is a single-stranded copy of the DNA sequence that plays a messenger role to help cells carry out instructions for making a protein. RNA consists of four nucleotides or bases (A, U, G, and C). The DNA T is replaced by the RNA U when copied.
SNP	A single-nucleotide polymorphism (SNP, pronounced “snip”) is a DNA sequence variation that occurs when a single nucleotide (A, T, C, or G) in a gene sequence is altered. SNPs are the most abundant variant in the human genome and are the most common source of genetic variation, with more than 10 million SNPs present in the human genome. They can also serve as biomarkers.
Somatic	Somatic cells include stem cells, blood cells, and other cell types. Changes to somatic cells are not permanent, meaning they cannot be passed down by generation. Somatic cell mutations include acquired alterations that can result from chemical or radiation exposure. Changes may also occur as cells are copied during growth or repair processes.