analysis
» Go there
» Go there
» Go there
» Go there
the dna code
The entire DNA code (referred to as the human genome) contained in each human cell is made up of long chains of roughly 3 billion nucleotides (represented by the letters A, G, C, and T). The nucleotides are arranged in a specific sequence and packaged up tightly into 24 separate structures called chromosomes that are located in the nucleus of the cell.
All life on earth is derived from information coded in DNA. The history of any species and the history of our ethnic groups or populations is, in part, written in our DNA and our risk of disease and resistance against the same is also, in part, written in the same code.
Human beings and all other living things are made up of cells and these cells contain the DNA code. The body's cells normally grow, divide, and multiply, and a vital property of DNA is that it can be replicated so that each new cell gets its own copy of the entire DNA code. As in any replication process, however, errors can and do occur when a cell's DNA is copied. Such errors are called mutations. Mutations may also be caused by factors within the cell or by harmful factors from the environment, such as radiation or chemicals.
As mutations in the DNA code occur again and again, the cumulative effect of many mutations may eventually lead to changes in physical appearance and body function. Though all life on Earth has a common origin some 3.7 billion years ago, millions of different species have since evolved because of many small changes that occurred in their DNA over time and then the selection of the environment of individuals best fit to live and procreate in it.
dna inheritance
Each human cell (except for eggs and sperm) contains two copies of 22 autosomal chromosomes, one copy from each parent, plus a set of two sex chromosomes, the X and Y chromosomes. Females have two X chromosomes whereas males have one X chromosome (from the mother) and one Y chromosome (from the father).
Eggs and sperm contain one copy of each autosomal chromosome and a single sex chromosome. At conception, the single set of chromosomes from the egg and the single set of chromosomes from the sperm are combined to produce a new genome with two copies of each chromosome. The variation in appearance between siblings is based on what combination of chromosomes they received from their mother and father.
ancestry
Our species, Homo sapiens, first appeared in Africa some 130,000 years ago. Starting at least 60,000 years ago, small groups of humans left Africa and colonized Asia, parts of Oceania, and Europe. About 14,000 years ago, the first humans appeared in the Americas. Since then, the ancestors of modern humans have populated almost every corner of the Earth. While Homo sapiens is considered to be a "young" species, meaning that most of the human genome is the same between individuals, there are some genetic differences between the major groups of humans that live in different parts of the world.
In some cases, genetic differences occurred because each group of humans moved to different environmental conditions. In most cases, however, genetic differences between groups are simply due to chance as genes were passed down from generation to generation in different human groups.
Based on what we know about the genetic differences among and within the major groups of humans living today, and using your deCODEme Genetic Scan results, we can use a well-established method for determining your ancestry. Click here to learn more.
If you want to learn more on how the various groups may have migrated out of Africa and populated the globe please follow this link
types of mutations
There are various kinds of DNA mutations, the most common of which result in changes at a single spot in the DNA code - so-called point mutations. In the Genetic Scan, we examine the variations in the DNA code caused by point mutations called single nucleotide polymorphisms (SNPs). Each SNP represents a single spot or point in the human DNA code that may differ between different groups of people. deCODE has identified specific SNPs that appear more often in people with certain diseases - using the Genetic Scan, we are able to determine whether you have any of the SNPs that have been linked to specific diseases. Click here to learn more.
Other mutations involve larger chunks of DNA that are deleted or inserted into the code. More rarely, chunks of DNA can be turned around backwards (inversion), or they can be switched with another chunk of DNA from another part of the code (translocation).
Mutations of DNA in germline cells (eggs and sperm) may be transmitted from parent to child, thereby giving rise to differences among individuals over a single generation. The vast majority of germline DNA mutations seem to have little or no effect on a person's health but some of these mutations may have an effect on an individual's fertility or the health of their children. Rarely, germline mutations occur that improve fertility and the health of children who receive the mutations from their parents. These mutations are more likely to be passed on to subsequent generations.
the genome as a mosaic
When egg and sperm cells are produced, the chromosomes inside these cells undergo a process called recombination. During recombination, segments of DNA code are swapped between the 22 autosomal chromosome pairs. So, although you received one complete set of chromosomes each from your mother and father, the chromosome set you inherited from your mother actually contains a mixture of your maternal grandparents' chromosomes and the set you inherited from your father contain a mixture of your paternal grandparents' chromosomes.
As you trace your ancestry, the number of your ancestors doubles at each generation: you have two parents, four grandparents, eight great-grandparents, and so on. Thus, your genome represents a mosaic of DNA segments inherited from these ancestors. Because segments of DNA are swapped with each generation, the segments of your DNA that you inherited from your ancestors get smaller and smaller as you move back through your family tree. You inherited whole chromosomes from your parents, large fragments from your grandparents, smaller fragments came from your great-grandparents, even smaller fragments from your great-great-grandparents, and so on. As a rule, the more distant the ancestor, the smaller the fragments of chromosome that you inherited from that ancestor.
With these concepts in mind, and using your deCODEme Genetic Scan results, we can estimate your relationship to other individuals (of your choice, of course) based on how well the segments of your chromosomes match. Click here to learn more.