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Being able to identify family history is important because it allows parents to assess the risk of their child inheriting a genetic disorder that runs in the family. Pedigrees are charts that can help to track the family history of a particular trait.
A carrier is a person who is heterozygous for a recessive trait, meaning they have one dominant and one recessive allele. If this recessive trait is for a disease, then they are considered a carrier for the disease. This person only expresses the dominant phenotype, but they still possess the recessive allele. To display the phenotype for that disease, someone would have to have two recessive alleles. It would be important to know who is a carrier if this person were to have a child with another carrier. Their children would then have a chance of inheriting this recessive trait from both parents and contracting the disease.
IN CONTEXT
What are the odds two heterozygous parents (carriers) would have an offspring that expresses only the recessive trait? How would you find this out?
To determine what the chances are, you would need to use a Punnett square:
If you cross two heterozygous people, the square shows there is a 25% chance that their child will inherit that recessive trait.
A genetic abnormality is a trait that a person can inherit that is an abnormal expression of that trait but doesn't necessarily cause a health problem.
EXAMPLE
A person that has six toes. It is an abnormal expression of a trait, but it's not going to cause that person any health problems.A genetic disorder, on the other hand, does cause health issues.
EXAMPLE
Huntington's disease is a genetic disorder that results in the breakdown of nerve cells in the brain that results in severe mental and physical degeneration. Huntington's disease is therefore termed a genetic disorder because it actually does cause health problems.Source: This work is adapted from Sophia author Amanda Soderlind.
