On average, people probably carry from 5 to 10 genes with mutations in each of their cells.
Problems happen when the particular gene is dominant or when a mutation is present in both copies of a recessive gene pair.
A person can have changes (or mutations) in a gene that can cause many issues for them.
Sometimes changes cause little differences, like hair color. Mutations in a gene usually end up causing that particular gene copy to not do its job the way it normally should.
A male child receives an X chromosome from his mother and a Y chromosome from his father; females get an X chromosome from each parent.
Genes are sections or segments of DNA that are carried on the chromosomes and determine specific human characteristics, such as height or hair color.Problems can also happen when several variant genes interact with each other — or with the environment — to increase susceptibility to diseases.If a person has a change in a dominant gene that is associated with a particular condition, he or she will usually have features of that condition.To understand how genes work, let's review some biology basics.Most living organisms are made up of cells that contain a substance called deoxyribonucleic (pronounced: dee-AHK-see-rye-bow-noo-klee-ik) acid (DNA).Individual sperm and egg cells, however, have just 23 unpaired chromosomes.You received half of your chromosomes from your mother's egg and the other half from your father's sperm cell.And, each of the person's children will have a 1 in 2 (50%) chance of inheriting the gene and developing the same features.Diseases and conditions caused by a dominant gene include achondroplasia (pronounced: ay-kon-druh-PLAY-zhuh, a form of dwarfism), Marfan syndrome (a connective tissue disorder), and Huntington disease (a degenerative disease of the nervous system).Because every person has about 25,000 different genes, there is an almost endless number of possible combinations!Heredity is the passing of genes from one generation to the next. Heredity helps to make you the person you are today: short or tall, with black hair or blond, with brown eyes or blue.