When is Genetic Testing Necessary?
Genetic testing has come a long way thanks to numerous advances in science. There are more than 2,000 diseases that can be detected through genetic testing including rare genetic disorders such as Duchenne Muscular Dystrophy wherein muscular dystrophy occurs progressively due to recessive X-linked gene and Fragile X Syndrome, a genetic condition that causes mental retardation. Advances in genetics have also made it possible to detect inherited mutations of genes commonly considered to have protective functions in the body like BRCA1 and BRCA2, two genes that can cause cancer of the breast and ovaries to be inherited.
Genetic testing is used to detect changes in genes and chromosomes. Genetic testing is also known as DNA testing and can be used to determine if a person is a carrier of a genetic disease, to test for genetic disorders in asymptomatic individuals, to confirm diagnosis in individuals with symptoms, and to find possible genetic disorders in unborn babies.
What is DNA?
Deoxyribonucleic acid or DNA is the hereditary material present in humans and in almost every organism. Majority of the DNA can be found in the nucleus of a cell although some of it can also be found in the mitochondria. DNA can replicate itself and during cellular division, it is important that the new cell has the exact copy of DNA found in the old cell.
Genetic disorders are caused by an abnormality in the gene or the chromosome, the organized DNA structure inside the cell. The genetic makeup of an individual is determined at conception and large scale deletions or duplications of segments of chromosomes become evident during this time.
Should you undergo DNA testing?
Some individuals are at more risk of being a carrier or actually having a genetic disorder than others. One’s family history and ethnic background are crucial factors in determining whether or not you should undergo genetic testing. A family history of a genetic disorder increases one’s risk of being a carrier or having the disorder itself. Some genetic disorders are also more common in certain ethnic groups like cystic fibrosis which is more common in Caucasians and Tay-Sachs disease which is often associated with Eastern European Jews.
A doctor may recommend genetic testing in case a couple is planning to have a child and either of them or a close relative has an inherited condition or in case there is already a child with a severe birth defect. A birth defect can indicate a genetic problem although it can also be caused by other factors. A pregnant woman over the age of 40 may also be advised to undergo DNA testing as advanced age increases the risk of chromosomal conditions like Down syndrome. Individuals exhibiting symptoms suggestive of a genetic disorder will also need to undergo testing to confirm the condition.
Common Genetic Disorders
Some genetic disorders are common especially in terms of ethnic background and family history. This includes Down syndrome, sickle cell anemia, and cystic fibrosis.
Down syndrome affects 1 out of 1,000 infants born worldwide. It is caused by an additional genetic material in chromosome 21 and is also called trisomy 21. Down syndrome causes mental retardation and specific physical characteristics such as flat face and slanting eyes.
Sickle Cell Anemia
Millions of people all over the world have sickle cell anemia. It is common in individuals with ancestors from Africa, Saudi Arabia, South America, Central America, Cuba, India, Italy, Turkey, and Greece. Sickle cell anemia is a disorder that affects the blood, particularly red blood cells.
Cystic fibrosis occurs in 1 out of 3500 births in the United States and in 1 out of 2000 births in the European Union. An individual must have one defective gene from each parent resulting in two defective genes to have the disease. Upon conception of 2 carriers of cystic fibrosis, there is a 25% chance of passing on the disease and 50% chance that the child will be a carrier. Cystic fibrosis affects the lungs and other organs including the liver, pancreas, and intestine.
Genetic testing can be a valuable tool in determining genetic disorders. The field of genetics has come a long way but there are still numerous studies ahead that can help improve the methods and results of genetic testing.
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