Biotechnology Applications in Human Genetics

When people think of biotechnology it’s usually things like genetic engineering and cloning which come most readily to mind. However, the field of biotechnology is actually much wider than genetic manipulation, including applications in agriculture, engineering and bioremediation as well as health and medicine.

Each of the four subdisciplines combines both biological and physical sciences to discover new information and come up with solutions to complex biological or environmental problems. In medicine, biotechnology applications include genetic testing and gene therapy, both of which involve the study or manipulation of genetic material. Both are also somewhat controversial subjects, but for different reasons.

Genetic testing involves the examination of an individual’s DNA, often to determine if their genetic material contains mutated sequences which may cause them to develop a serious disease. Tests have been developed for certain genetic disorders, including Huntington’s disease, sickle cell anemia, and cystic fibrosis, which can detect gene mutations associated with those diseases. Other tests can detect the presence of genetic mutations linked to the development of certain cancers, including breast, colon, and ovarian cancer.

Genetic testing can also be used to determine the sex of an unborn child, carry out prenatal diagnostic screening, diagnosing carriers of a disease (in cases where individuals require two copies of a mutant gene to develop a particular disease), and carry out forensic work.

There are several controversial issues relating to these biotechnology applications. One is that some diseases for which genetic testing is available are not yet curable or preventable, leading to a dilemma for medical practitioners and individuals undergoing testing.

Another issue which poses ethical dilemmas for scientists and the public is the concept of so-called designer babies, as genetic testing allows parents the opportunity to choose in advance the sex of their child, or terminate pregnancies in which a fetus has been diagnosed with a certain disease.

Gene therapy is a very different type of genetic biotechnology application which involves the manipulation of genetic material, and the genetic manipulation of organisms, in the attempt to cure specific diseases. Gene therapy involves using normal, unmutated genes to replace copies of defective disease-causing genes, or in some cases to initiate or bolster an immune response to a specific disease (such as cancer).

Gene therapy treatments can be implemented in an individual in one of two ways.

The ex vivo method of treatment involves removing a sample of a patient’s blood or bone marrow, and growing the cells in a laboratory. The cells are then exposed to a virus which carries a normal copy of the relevant disease-causing gene. The virus then enters cells, and introduces the normal gene into cellular DNA. Next, the cells go through a second growth period before being injected back into the patient. After a successful gene therapy treatment, the patient has a normal copy of the relevant gene and is able to successfully make the protein the gene codes for.

In the in vivo method of treatment, cells are not removed. Instead, the patient is ‘infected’ with a non-infectious virus which has been genetically engineered to carry the required genetic material. The virus infects cells and introduces the gene into cellular DNA.

Currently the use of gene therapy is largely experimental, with well over five hundred clinical trials having been initiated in the last one or two decades. Many of these focus on treating various types of cancer, as well as genetic disorders.

There are problems and controversies associated with gene therapy, as with genetic testing. Perhaps the most controversial issue is that while non-infectious viruses are used as vectors, there have been very rare occasions where a virus has caused serious infection in patients.

Other problems include the fact that many genetic disorders are caused by disruptions in multiple genes, making it difficult, if not impossible, to devise effective treatment using current methods. In addition, there are many diseases which have environmental as well as genetic causes, such as cancers which are affected by diet and lifestyle choices.