While CML is not an inherited disease, scientists hope to one day use the same concept to treat or cure genetic diseases. One step in that process was the Human Genome Project, which could give scientists the tools they need to change the future of genetic research.

The Human Genome Project (HGP) was an international effort to map the entire human genome, all 3 billion base pairs of it. When it started in 1990, scientists set a goal of 15 years to complete the project but completed it in 2003, with two years to spare. Many volunteers gave blood to provide DNA for the project. Some of this blood was not used, and the labels on the blood tubes that were used were intentionally removed so no one would know exactly whose DNA was being sequenced. The final sequence, which has been published on the Internet, is a combination of many of the volunteers’ DNA. Because 99.9% of everyone’s DNA sequence is exactly the same, having a sequenced human genome has already made the job of finding genes that cause some genetic diseases easier. In the future, scientists hope to find what they suspect is the genetic basis of other diseases such as heart disease, diabetes, and some mental illnesses. Some genes that are involved in cancer had already been identified before the HGP started, but scientists also hope to find even more with help of the sequence. Not only do scientists hope to find the genes that cause disease, but they also hope to develop drugs and other treatments to specifically target these diseases and their faulty genes.

Scientists were surprised at some of the results of the HGP. Before the project began, some scientists estimated that the human genome would contain as many as 100,000 genes. Imagine everyone’s surprise when the final estimate was less than half of that—20,000 to 25,000 genes.

Except for science fiction writers, no one really gave a thought to the idea of cloning humans until researchers at the Roslin Institute in Scotland produced the first cloned mammal, a sheep named Dolly, in 1997. The type of cloning that produced Dolly is called reproductive cloning. If cloning is mentioned in the media, the reporters are usually talking about reproductive cloning.

Reproductive cloning is the act of making a genetic twin of a currently living or previously living organism. Dolly was produced by taking the nucleus, including its DNA, from an udder cell of an adult sheep. This nucleus was then implanted into another cell that had its nucleus removed. In order to make this recombined cell start to divide, researchers had to apply chemicals or electric shock to the cell. Once the cell started to divide, the cell was implanted into another sheep that served as a surrogate mother for the developing embryo. This technique is called “somatic cell nuclear transfer,” or SCNT.

Dolly’s birth surprised some scientists who were convinced that once cells have received instructions to turn into a particular type of cell (called differentiation)—for example, a heart cell, lung cell, or udder cell—there would be no way to reprogram the cells to become something else. It turned out, however, that it was possible to reprogram the cells. But, the news was not all good. Even though the type of sheep Dolly came from usually live to be about 11 or 12 years old, Dolly died at the age of six. When she died, Dolly was suffering from severe arthritis and lung cancer, diseases that usually show up in older animals.

In fact, many of the cloned animals that have been produced to date have suffered much higher rates of death, deformity, mental diseases, and disability than other animals their age that are conceived naturally. Scientists believe this could be a result of incomplete reprogramming of the adult cells used to make the clones. Or it could be due to the fact that nuclear DNA is not the only DNA that exists in the cell. There are also short strands of DNA found in the mitochondria, an organelle that is often called the powerhouse of the cell. When Dolly was created using SCNT, the cell with the nucleus removed still had DNA present in its mitochondria. Because of the presence of mitochondrial DNA, Dolly was not a true identical clone of the animal from which she originated. In fact, none of the clones that have been made so far using the SCNT technique are identical to the animal they came from because of the presence of mitochondrial DNA.

Reproductive cloning is not the only type of cloning, however. DNA cloning, or recombinant DNA technology, is a way to make many copies of the same gene and has been around since the 1970s. Researchers use this method when they need many copies of the same gene so they can study it. Th e section of DNA under study is usually put into a bacterial cell (although yeast and mammalian cells can also be used). Th e bacterial cell makes many, many copies of itself and, in the process, many, many copies of the gene in question. Researchers for the Human Genome Project used bacterial host cells to make copies of genes so they could sequence them. DNA cloning is also important in the study and delivery of gene therapy.

Another type of cloning is therapeutic cloning. Th is type of cloning involves creating human stem cells for a particular patient from their own DNA. Stem cells are cells that have not yet differentiated, which means that they can turn into any type of cell in the body, whether it is a heart, brain, or bone cell. In therapeutic cloning, scientists take the nucleus out of a human egg and implant the nucleus of another type of cell (a skin or liver cell, for example). This is the same technique (SCNT) that was used to produce Dolly the sheep. Chemicals are then used to make the egg start to divide. After about five days, stem cells can be harvested from the dividing embryo. Scientists hope that, one day, stem cells may be able to be used as replacement cells to treat diseases such as heart disease, Alzheimer’s disease, and cancer. They also hope to be able to grow replacement organs in the laboratory that could one day be used for organ transplants. For example, if scientists were able to take cells from a person who needs an organ transplant and clone those cells, the scientists would be able to harvest stem cells that would be an identical genetic match for that person. Theoretically, this procedure could eliminate the danger of organ rejection.

Even though creating cloned humans is not the goal of therapeutic cloning, harvesting the stem cells does destroy the dividing embryo and this raises ethical questions. Many scientists have expressed a strong belief that trying to clone humans would be highly unethical. First of all, not many of the cloning experiments in animals have been successful thus far. Only one or two cloning experiments out of 100 produce a living clone. And of the living clones born so far, many have had physical problems or deformities, while others have died much younger than their counterparts that were conceived naturally.

Unlike cloning, genetic manipulation of plants has gone on for centuries. But the process of crossing plants over many generations to produce hybrids that possess desired traits takes time. Scientists can now speed up that process by inserting the genes from one plant into another plant. The goal of making hybrids and genetically manipulating actual genes is the same—to make plants with desired characteristics such as resistance to insects and disease, improved nutrition and taste, and stronger and more plentiful crops.

Creating a transgenic animal, or an animal that has had genes from another animal spliced
into its genome, involves manipulating and preparing a gene in a lab,
injecting it into the egg of an animal, and implanting that egg into a surrogate mother.

A type of corn, called Bt corn, for example, contains a gene that allows it to make its own insecticide, a chemical that kills insects that try to eat the corn plant. The inserted gene is called a transgene. Plants that contain transgenes are sometimes called genetically modified (GM) crops. In 2006, more than 10 million farmers in 22 countries planted more than 250 million acres of GM crops. Some of the crops being grown or tested include rice that has had iron and vitamins added to it, sweet potatoes that are resistant to a sweet potato virus, and a variety of plants that are capable of surviving very hot or very cold weather. But scientists are also working on a strain of bananas that can produce human vaccines for infectious diseases such as hepatitis B, cattle that are resistant to mad cow disease, plants that can produce a new type of plastic, and fish, fruit trees, and nut trees that mature more quickly. Several concerns about GM crops have been raised, however. Some people worry about the unintended, long-term effects of growing and eating GM crops such as spreading or contaminating the transgenes through pollination. There are also concerns about the loss of biodiversity, as well as the long-term effects on people’s heath. People may also object to eating animal genes in plants and vice versa.

As they have done with plants, farmers have long bred animals for advantageous traits. As with plants, however, these deliberate crosses to produce cows that provide more milk or chickens that lay more eggs, for example, take time. Scientists are now producing transgenic animals, too. Transgenic animals have had genes from another species spliced into their genome.

Researchers have been doing genetic manipulation for a long time with mice to make animal models of human diseases, but now they are also doing it in order to produce proteins or drugs that can treat human disease. Scientists are using cows, sheep, goats, and chickens for this research because then the drugs can be produced in the animal’s milk or, in the case of a chicken, its eggs. Producing drugs for human consumption from animals is called pharming. The word comes from the combination of farming and pharmaceuticals (drug making). Scientists have produced, or are working on producing, human proteins that can help treat cystic fibrosis, hemophilia, osteoporosis, HIV, and malaria. They are also working on animals that can produce certain antibodies that can be used to make vaccines against specific diseases.

Like GM crops, some people have concerns about genetically modified animals. These concerns include effects of pharming on the animal’s welfare. Genes are delivered to the animal’s genome via retrovirus, so there is the possibility that the delivered gene will be inserted into one of the animal’s functioning genes, accidentally turning that gene off. Also, only about 1% of transgenic eggs turn into animals that express the inserted gene in a large enough quantity to be useful. The other eggs either do not form correctly or the animal that is born does not express the transgene. So what happens to these other animals?

Along with advances in GM crops and pharming, scientists also envision a future where each individual has their entire genome mapped. Doctors could then prescribe diet or life-style changes, medications, or checkups designed to keep each individual as healthy as possible based on the information found in their DNA. Scientists also hope to find new medications to treat diseases such as diabetes, heart disease, and mental illnesses, like schizophrenia, as well as other genetic diseases that do not currently have treatments.

Being able to go to your doctor and with a drop of blood be told exactly what is contained within your DNA may sound like science fiction, but it is quickly becoming a possibility with the invention of DNA chips. Smaller than a postage stamp, these chips are made up of a silicone or glass plate that contains single-stranded DNA fragments. The sequences of the DNA fragments on the plate are known. In theory, a scientist or a doctor could put a sample of DNA taken from a patient’s pricked finger onto a DNA chip and tell what the patient’s DNA sequence is, depending on which single-stranded DNA fragments the patient’s DNA sticks to.

A DNA microchip, like this one, helped researchers detect two types of leukemia in a 1999 trial test.
The microchips, which are generally pieces of etched glass layered with pieces of genes, interact
in specifi c ways with the DNA of whatever material is placed on them.

Who knows where the future of genetic research may lead? It is possible that one day patients may be able to find out during a doctor visit that they are predisposed to developing heart disease, Alzheimer’s disease, cancer, or some other common disease that has a genetic component—all before they leave the doctor’s office, much less before they start to show symptoms. In the future, doctors may even be able to cure these, or other, genetic diseases. Scientists may figure out how to clone threatened or endangered animals. Almost anything is possible. After all, only 50 years ago, scientists did not even know what DNA looked like—and it is guaranteed that there is still a lot to be learned.