Chat Transcript: Genetic Sequencing

January 5, 2000
Web posted at: 4:00 p.m. EDT

Slotnick is an associate professor of obstetrics and gynecology at Eastern VA Med. School. He is board certified in both ob/gyn and medical genetics. At EVMS, Dr. Slotnick works with prenatal diagnosis, fetal therapies, pre-implantation genetics, and high-risk pregnancies.

Slotnick joined the chat via telephone from EVMS and CNN.com provided a typist. The following is an edited transcript of the chat.

Chat Moderator: Welcome Dr. Slotnick!

Dr. Nathan Slotnick: Thank you for having me today. I'm looking forward to this next half-hour.

Chat Moderator: What is the genome project?

Dr. Nathan Slotnick: The Genome Project is the combined efforts of 1000s of scientists around the world and particularly in the US, whose goal is to sequence the DNA of the human genome. The DNA has an estimated 100,000 genes, many which have not been described in sequence or function. The goal of the Genome Project is to define the sequence so the next step will be to try to define the function

Chat Moderator: How many people are involved in this project and how long has it been going on?

Dr. Nathan Slotnick: The Genome project has been going on for 8 or 9 years. Literally 1000s of people have been involved

Chat Moderator: Would you please explain to us what is sequencing of DNA?

Dr. Nathan Slotnick: The DNA of the human genome is made up of billions of pieces of code. The code is made up of 4 letters, and the order of those letters defines the function of any particular gene. The genes act in cells by telling the cell precisely what to do; genes acting in liver cells tell liver cells to do certain things. Different genes in muscle cells tell those muscle cells to do different things. Sequencing of the DNA allows us to define where genes begin and end in the code and to begin to define what those genes do in the different cells.

Chat Moderator: What is the significance of sequencing chromosome 22?

Dr. Nathan Slotnick: In each of the cells of our body, there are 46 chromosomes. 23 come from our father and 23 from our mother. They are organized in pairs. That means then that there are 23 pairs of chromosomes in each cell. The DNA that makes us what we are is packaged in those chromosomes. Chromosome 22 is the smallest chromosome in the human genome containing the smallest amount of DNA. But even that chromosome has a huge amount of genetic information packaged within it. The estimated amount of genes on chromosome 22 is about 1000.

The genes on chromosome 22 can have many different roles within the cells. There are some genes that have been associated with brain function, some with muscle function, and some genes associated with lung function.

Chat Moderator: What does this discovery mean to the medical community?

Dr. Nathan Slotnick: This is the first of the chromosomes to be sequenced. And it is best viewed as a milestone in the progress and success of the genome project. Over the next 3 or 4 years, the remainder of the chromosome DNA sequences will be finished. And we'll be able to put all this information together.

It is also a remarkable statement about the successful collaboration between laboratories in different countries. These laboratories are cooperating in a joint venture. They may not have cooperated prior to this project being initiated. The ultimate goal of completing the sequence is that the target and success that all the laboratories have.

Question from healthperson: Does this research bring you closer to curing diseases or preventing them completely?

Dr. Nathan Slotnick: We are all predisposed through our DNA genetic makeup to certain conditions and diseases. By completing the DNA sequence of the human genome project, we will be able to define those diseases better and identify those people for both cure and true preventative medicine.

If I know years in advance that I have a risk increase of developing atherosclerosis, I would be able to choose diets and activities, and my doctor would be able to choose medications that would give me a healthier life. That is the preventative answer. Before too long, we will also be able to design medications specifically for people based on their own genetic makeup. Ultimately we may be able to correct the DNA sequence itself to "cure" a genetic disease.

Question from hexx: But will completing the sequence allow one to tailor their (or others') DNA to stop diseases entirely?

Dr. Nathan Slotnick: The completion of the sequencing will only be the first step. We will need to understand better how the different genes interact and how they are controlled. Only then will we be able to anticipate true genetic disease cure.

Question from haf: What will the completion of the project mean to the average citizen?

Dr. Nathan Slotnick: Probably not much at the beginning. Although the sequence itself will be available for researchers to look at, the understanding of the meaning of the sequence will take time to elucidate.

The average citizen will realize benefits from the advancing technologies sooner than the understanding the sequence will have an impact on their lives. The analogy that best fits would be the advances in computer technology that began with the space program back in the 60s. The affect on the average person's life is hard to anticipate

Question from LEON: Is it fair to say that the Human Genome Project will laid the bases for the medicine of the next 100 years?

Dr. Nathan Slotnick: The medicine that is practiced today will change dramatically in the next decade. As we understand better how diseases occur, we will also understand better how to cure them. The application of this genetic technology will make it necessary for all physicians to become "geneticists." That is a tremendous responsibility for educators in medicine to keep their students, or medical students, current.

Question from Spartacusss: What is your opinion on companies that are trying to put patents on the sequenced human genes they map? Are they allowed to patent nature? Is that ethical?

Dr. Nathan Slotnick: I guess the answer would have to be this: I am not a lawyer. And I don't have much input in how laws are written, particularly patent laws. But having said that, I can't understand the long-term societal benefit of patenting DNA sequences. Ultimately the understanding of those sequences will have a much broader effect in an open and free access environment. As far as ethics goes, I would have difficulty finding patenting of DNA sequences medically ethical.

Chat Moderator: Do you have any final thoughts?

Dr. Nathan Slotnick: Because these topics are topics that need society's input, I look at this opportunity today as a way of beginning the dialog, and continuing the discussion between scientists and clinicians and the general public who will ultimately be affected by this work. I have enjoyed the discussion!

Chat Moderator: Thank you Dr. Slotnick for joining us today.

Dr. Nathan Slotnick: I enjoyed it! Goodbye and thank you very much!