Basics of genetic testing
Genetics is a scientific field in the area of biology that deals with genes – their molecular structure and function, their expression and occurrence in populations, connected to heredity and the study of kinship among organisms.
Who and what we are is largely determined by our genetic makeup or DNA. DNA is essentially present in the nucleus (core) of every cell of our body. It determines our appearance, how we respond to the environment factors (e.g. medicine, sunlight, nutrients, physical effort ...) and to a certain extent also our behaviour. Our genetic makeup is unique – comparable to a fingerprint, because in the whole world no two persons have an identical genetic makeup (except identical twins).
Not so long ago, people did not have much knowledge about genetics and used experiments to learn how certain properties are inherited. By trial and error they learned how to obtain the most resistant species of plants and how likely it is that a particular trait is expressed. Today, the base of genetic knowledge is immense and increasing each day, because we have advanced techniques that can read person’s genome and understand what that means for us. With these techniques we can determine family relationships, our tendencies to develop a certain disease, the personal response to medicaments and nutrients, discover hidden potentials and talents, and realize many other important things about ourselves.
What are genes?
Genes contain the information written in the human hereditary material (DNA) and they are of utmost importance for the growth and development of an individual. They located in 23 pairs of human chromosomes. Chromosomes appear in pairs; one comes from the mother and the other one from the father. Thus, every person has two copies of a gene. One copy is called an allele. The two alleles can be identical or different.
What is written in the genes?
Genes play an essential role in passing hereditary characteristics from one generation to the next. Since they are passed from parents to their children, they are responsible for the similarities between parents and children, and give basis for the creation of new human beings. The products of the genes are proteins which are the main macromolecules in the organisms. Proteins are comprised of 20 different smaller molecules called amino acids. The genes encode the correct amino acid sequence and the information on the amino acid type. The specific amino acid sequence encoded by a gene results in a specific protein. In this way, the genetic makeup, together with the environmental influences, forms the uniqueness of each individual.
What are mutations?
In Latin, mutation means change. When talking about mutations in genetics we talk about the change in the DNA sequence. This can happen in many ways – a nucleotide can be inserted into the sequence, it can be deleted or simply substituted by another one. We call such a substitution a SNP. All SNPs were thus created by some mutation. If a mutation occurs in a certain gene, the gene can become inactive (it does not make the correct proteins) or, rarely, make a new and better protein. In this way, an organism with a different trait is created, having a selective advantage for survival. Thus, mutations are DNA "errors" which appear by chance, and at the same time represent the engine of evolution.