The cells in our body use DNA as the basic instruction manual for cell function. You could think of DNA as a blueprint for the cell. Blueprints do not pour the foundation or lay any bricks for a new building, but without the blueprint, the building wouldn't exist. DNA works in basically the same way. It is the set of instructions for the cell to carry out all of its functions. There are two molecules in the cell that perform most of the work: RNA and protein. RNA performs many cellular functions, but proteins are the real workhorses of the cell. On the molecular level, RNA is very similar to DNA. RNA is made through a process called transcription, where the cell copies the information from the DNA into a different molecular format. One of the functions of RNA is to be the molecular code for the protein, in a process called translation. Proteins are made up of a long string of amino acids, which are encoded in the RNA sequence. The amount of RNA that is made by a gene determines how much protein is made from that RNA. The amount of RNA that is made from a DNA sequence is referred to in genetics as the expression level of a specific gene. A gene that shows high expression makes lots of RNA whereas a gene with low expression makes a little RNA. Once proteins are made, they perform most of the work the cell needs to function on a day-to-day basis.

Even though DNA itself does very little in the cell, it serves an extremely important role. The sequence of the DNA determines the sequence of both RNA and proteins that are made from the DNA blueprint. If there is a change in the sequence of the DNA, like a variant, it can change the sequence of the RNA and the protein. This can have important consequences on the way that RNA and protein function in the cell. Some variants change the way that a protein functions by changing the protein sequence. Other variants change the amount of RNA that is made from the DNA sequence, leading to too much or too little RNA or protein. The majority of the variants we inherit have little impact on our health. However, specific variants can change the way our cells function, leading to changes in the way we look, changes in the way we respond to certain medications, or disease.