Genetic or biological disorders can start even before a person is born. A genetic disorder is a biological issue that is passed on from parent to offspring. In other words, this type of disorder is inherited because it can be caused by a person's genes.
A person's genetic history thus can be used to determine whether or not that individual is more likely to have a certain genetic disorder. Genetic disorders can occur on two different levels:
EXAMPLEDown Syndrome, or “Trisomy 21,” is a disorder in which a person has three of the 21st chromosomes instead of the two that he or she should normally have. This results in certain recognizable physical characteristics, such as a rounder face or slanted eyes, as well as cognitive impairment, which may vary over time but can result in different types of learning deficiencies.
EXAMPLEThere can also be defects in the sex chromosomes as well. This mainly occurs in the X-chromosome, which results in Turner Syndrome or Klinefelter Syndrome.
There can also be problems that occur before birth, leading to either biological or genetic disorders. These issues are not inherited in the same way as genetic disorders.
Disorders that originate in the womb are called congenital problems, and are often due to environmental factors that are introduced at that time.
Though the factors are environmental, they can have long-lasting genetic or biological effects because the prenatal time--the time when the child is in the womb--is a sensitive period. Thus, there is an increased susceptibility to environmental influences that can affect a person's development.
EXAMPLEOne disorder caused by a teratogen is fetal alcohol syndrome, which occurs as a result of heavy and repeated drinking of alcohol while a child is still in the womb. The effects of this are low birth weight, a smaller head (also meaning a smaller brain being developed), body defects, and mental or behavioral retardation.
Source: Adapted from Sophia tutorial by Erick Taggart.