Examples of DNA Genetic Disorders

Genetic disorders come in all shapes and sizes. The presence of a genetic disorder might cause physical abnormalities, such as in Marfran's Syndrome, mental defects, as in Down Syndrome, or both, as with Prader-Willi Syndrome. Genetic disorders are caused by extra copies of chromosomes, missing chromosomes or mutations in the specific locations of one or more genes. Many such mutations simply cause a miscarriage, so the number of children actually born with genetic disorders is a subset of those actually conceived.

Extra or missing chromosomes

The easiest genetic disorders to detect are those that involve missing chromosomes or extra copies of chromosomes; the best-known genetic disorder of this type is Down's Syndrome. In Down's Syndrome, an extra copy of the 21st chromosome is present. This disorder causes mental retardation and the early-onset Alzheimer's disease. Down's Syndrome is detectable in-vitro, and as a result, 90% of fetuses with this abnormality are aborted.

Mutations

Many other genetic disorders are caused by specific mutations of one or more chromosomes. Some such disorders are very common. Color blindness, for instance, is a result of a mutation on the X-chromosome that makes it impossible for those affected to see specific colors. Since the mutation is on the X-chromosome, women are generally not affected, as the "damaged" X-chromosome is inactivated in favor of the undamaged chromosome. Other examples of mutation-related genetic abnormalities are hemophilia and sickle-cell disease.

There are other types of genetic abnormalities than those listed here. For example, some disorders are caused by wholesale deletion of gene sequences or epigenetic factors. With the completion of the Human Genome Project, it is an exciting time for those in the biomedical science field. Many of these genetic disorders are likely to see advances in treatment within our lifetimes.