GENE DISORDER

Gene mutation occurs when the cells contain changes or variants in the information of the gene. It usually happens when the cells are aging or have been exposed to certain chemicals or radiation. Cells would identify the mutation and repair them by themselves. However, gene mutation can cause cancel or other illnesses. If the gene mutation exists in egg or sperm cells, children can inherit the mutated gene from their parents.

Researchers have identified more than 4,000 diseases that are caused by genetic variants. A person will not really get the disease although he has the genetic mutation. Because a person inherit a gene from each parent, if the person get one disease gene and one normal gene, the disease gene usually does not cause any problem as normal gene can allow your body to make the normal protein it needs.

On average, people probably carry from 5 to 10 variant or disease genes in their cells. Harm occurs when there is a dominant gene or same recessive disease gene is present on both chromosomes in a pair. Harm can also occur when the variant genes interact with each other or the environment. This has increase vulnerability to diseases.

A person will usually have the disease if he or she carries the dominant disease gene. There is 50 % chance for his or her children to inherit the gene and get the disease. Achondroplasia (a form of dwarfism), Marfan syndrome (a connective tissue disorder), and Huntington disease (a degenerative disease of the nervous system) are example of disease caused by a dominant gene.

Carriers are people who have one recessive gene for a disease and don’t usually have the disease because they have a normal gene of that pair that can do the job. However, there are 25% chance for the child to get the disease if both the parent are carriers. Cystic fibrosis (a lung disease), sickle cell anemia (a blood disease), and Tay-Sachs disease (which causes nervous system problems) are caused by recessive disease genes from both parents coming together in a child.

Some recessive genetic mutations are carried only on the X chromosome. The guys will usually develop the disease because they have only one X chromosome. On the other hand, girls would need to inherit two copies of the recessive gene to get the disease because girls have two X chromosomes. X-linked disorders include the bleeding disorder hemophilia and color blindness.

Sometimes the new cell gets too many or too few chromosomes when the sperm and egg unite. Most children born with Down syndrome, which is associated with mental retardation, have an extra chromosome number 21.

People can have genetic testing if they worried that they might carry certain variant genes. Pregnant women can also have tests done to see if the fetus they are carrying might have certain genetic illnesses. A sample of someone's blood, skin, or amniotic fluid, and is taken and checked for signs of genetic diseases or disorders in a genetic testing.