Cracking the Code of Life
Cracking the Code of Life is a video published by PBS in 2001, and is available to watch for free online. The video observes the newly completed Human Genome Project, and discusses the pros and cons of knowing the billions of letters that make up an individual’s unique DNA sequence.
The Human Genome Project is a collection of the entire sequence of human DNA. With a completed Human Genome, doctors will have an easier time identifying illnesses that someone has because they can match the individual’s DNA to that of the code recorded in the Human Genome. The Human Genome helps us confirm illnesses and diseases by comparing the common code to an individual’s. This can also be used to compare the human code to codes of other species, to determine the differences and comparisons between the genetic sequences.
Before the Human Genome Project was created, doctors used a differed form of gene mapping to help determine particular traits in individuals. In old gene mapping, a DNA sequence wasn’t needed. Instead, doctors looked at family pedigrees and recorded information about visible phenotypes that older family members had in order to determine an estimate for what traits a person might have.
One example of a genetic disorder in which using the Human Genome is very beneficial is Tay Sach’s disease. Tay Sach’s is a rare and fatal disease in infants that involves a mutation in only one letter of the genetic sequence. It is a recessive trait that both parents must obtain in order for the infant to carry. Around six months of age, a child’s nerve cells will begin to deteriorate as well as mental and physical abilities. This is because the one chromosome that is supposed to control brain development is replaced with another chromosome, so many gangliosides form around the brain. This becomes increasingly worse until the child dies around age 4 or 5.
In the case of the Lord Family, Hayden’s parents noticed a physical difference in his development, and doctors were able to use the Human Genome Project to compare the sequences and find the difference in one letter of the sequence to confirm that Hayden had Tay Sach’s disease. Hayden’s aunt noticed that her youngest daughter was acting similarly to Hayden. The Human Genome Project was beneficial to the Lord Family because doctors could verify that the aunt’s daughter had Tay Sach’s as well.
After the Human Genome Project was completed, researchers became interested in comparing the DNA sequences of Icelanders because many of them have common ancestors and are closely related. Comparing the sequences of many people with similar DNA sequences would help to determine which codes cause particular phenotypes, because there are fewer differences within the sequences that could cause a specific trait or disease. Researchers requested permission from every citizen of Iceland to study their DNA. However, this process is very invasive, and was very controversial among Icelanders, many of whom did not feel comfortable releasing their personal information to various scientists. For more information on the Icelandic controversy, click here.