Genetic pertains to the study of human genes, the discrete parts of DNA that shape individual and species characteristics. In a human being, probably less than 1% of a person's DNA actually is utilized to provide instructions to human cells. The study of genetic diseases comprises the medical specialty of medical genetics. A specialist in medical genetics is a geneticist. On House, M.D., Jeffrey Cole was a geneticist.
Several human diseases are the direct result of genes inherited from a person's parents. Some diseases and disorders are almost always transmitted from parents to children of both sexes (e.g. dwarfism). Others require both parents to pass a particular recessive gene to the child (e.g. cystic fibrosis). Still others are almost only passed on to males, but the defective gene is actually on the mother's X-chromosone (e.g. hemophilia, color blindness).
In addition, some genes make it more likely that a patient will develop a particular disease. This includes conditions such as diabetes mellitus, heart disease and most forms of cancer. As such, doctors taking a medical history almost always ask what diseases the patient's parents and other close relatives are known to have suffered from.
Once a patient has been diagnosed with a genetic condition, there is generally no treatment that will eliminate the disorder. Patients with such diseases generally have to undergo a lifelong course of treatment. For example, sufferers of cystic fibrosis, which causes the mucous to become thickened, must undergo a course of several medications designed to both thin out the mucous so the patient can breath normally, as well as other medications that assist the patient to digest food.
Some sub-specialties of medical genetics are:
- Clinical genetics - the treatment of patients with genetic disorders
- Metabolic and Biochemical genetics - the study of genetics that affect the patient's metabolism or physiology.
- Cytogenetics - the study of malformed chromosomes
- Molecular genetics - the practice of attempting to isolate the gene or genes that may be responsible for a genetic disease in the DNA of sufferers
- Mitochondrial genetics - the study of defects in the DNA of mitochondria and their related diseases
- Genetic counselling - the treatment of persons who have been diagnosed with a genetic illness at the screening stage before symptoms develop