DNA Mutations

Example:

One look around a room tells you that each person has slight differences in their physical make up — and therefore in their DNA. These subtle variations in DNA are called polymorphisms (literally "many forms"). Many of these gene polymorphisms account for slight differences between people such as hair and eye color. But some gene variations may result in disease or an increased risk for disease. Although all polymorphisms are the result of a mutation in the gene, geneticists only refer to a change as a mutation when it is not part of the normal variations between people.


How Do Mutations Occur?
Copying errors are introduced when DNA replicates itself.
Everyone acquires some changes to their DNA during the course of their lives. These changes occur in a number of ways. Sometimes there are simple copying errors that are introduced when DNA replicates itself. (Every time a cell divides, all of its DNA is duplicated so that the each of the two resulting cells have a full set of DNA.) Other changes are introduced as a result of DNA damage through environmental agents including sunlight, cigarette smoke, and radiation. Our cells have built in mechanisms that catch and repair most of the changes that occur during DNA replication or from environmental damage. As we age, however, our DNA repair does not work as effectively and we accumulate changes in our DNA.
Germline mutations are what cause diseases to run in families.
Some of these changes occur in cells of the body — such as in skin cells as a result of sun exposure — but are not passed on to children. But other errors can occur in the DNA of cells that produce the eggs and sperm. These are called germline mutations and can be passed from parent to child. If a child inherits a germline mutation from their parents, every cell in their body will have this error in their DNA. Germline mutations are what cause diseases to run in families, and are responsible for the kind of hereditary diseases covered by Genetic Health.
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What Kind of Mutations Are There?
A gene is essentially a sentence made up of the bases A, T, G, and C that describes how to make a protein. Any changes to those instructions can alter the gene's meaning and change the protein that is made, or how or when a cell makes that protein. There are many different ways to alter a gene.

DNA expression mutation: There are many types of mutations that change not the protein itself but where and how much of a protein is made. These types of changes in DNA can result in proteins being made at the wrong time or in the wrong cell type. Changes can also occur that result in too much or too little of the protein being made.