Understanding the Genotype and Phenotype of a Genetic Carrier
A genetic carrier is an individual who has inherited one copy of a type of gene called a recessive gene that does not have physical or biochemical characteristics associated with the gene. For example, a person may inherit a gene for cystic fibrosis without developing the disease. However, genetic carriers can pass this gene onto their children.
Individuals who are interested in knowing if they are a genetic carrier can talk to their doctor about genetic carrier screening. Genetic carrier screening is a blood test that analyzes your DNA and indicates whether or not you carry a gene associated with a certain genetic disorder.
If you have been identified as a genetic carrier, it is important to understand your unique genotype and phenotype.
What Is a Genotype?
Genes hold a set of instructions that guide your growth and development. Genotype refers to the pair of genes for a certain trait that an individual inherits, one from each parent. For each trait, the two copies of the gene affect how the trait is expressed. For example, eye color genes from your mother and father interact to determine whether your eyes will be blue, brown, or hazel.
There are two different types of genes that create the unique expression of a trait, and variations in each gene also contribute to genetic expression. The two types of genes are:
Recessive genes – Recessive genes are genes that require two copies in order to express the related trait. If an individual inherits a recessive gene from one parent, and a dominant gene from the other parent, the recessive trait will not be expressed. If a second identical copy of the recessive gene is inherited, the trait will be expressed.
Dominant genes – Dominant genes are genes that only need one copy in order to express the related trait. If coupled with a recessive gene, the trait associated with the dominant gene will always be expressed.
What is the Genotype of a Genetic Carrier?
The genotype of a specific trait of a genetic carrier consists of one recessive gene and one dominant gene.
What Is a Phenotype?
Phenotype is the physical or biochemical manifestation of genes. Examples of phenotype include:
Certain diseases, such as cystic fibrosis or Down syndrome
What is the Phenotype of a Genetic Carrier?
The phenotype of a genetic carrier for a genetic condition is always asymptomatic, meaning that the individual does not present any signs or symptoms of the disorder. Although the genetic carrier is safe from developing the condition, they are at risk of passing the gene onto their children. Most people do not know they carry a recessive gene for a disease until they have a child with the disease.
Want to Learn More About What it Means to Be a Genetic Carriers?
If you think that you may be a genetic carrier, or if you’d like to learn more about what it means to be a genetic carrier, talk to your doctor.