Home > Genetic disorder

• They may be caused by an unwelcome mutation, as are most cancers.
• There are genetic disorders caused by the accidental duplication of a chromosome, as in Down syndrome and Klinefelter's syndrome, or repeated duplication of part of a chromosome as in Fragile X syndrome.
• The defective genes are often inherited from the person's parents. In this case, the genetic disorder is known as a hereditary disease. This can often happen unexpectedly when two healthy carriers of a defective recessive gene reproduce, but can also happen when the defective gene is dominant.

Genetic disorders are frequently due to the change of a single DNA base in a gene, resulting in an enzyme or other protein either not being produced or having altered functionality. This can be trivial and relatively harmless in its effects, such as color blindness, or lethal such as Tay-Sachs. Other disorders, though harmful to those afflicted with them, appear to offer some advantage to carriers; as in carriers of sickle cell anemia and thalassemiaThalassemia ( American English) Thalassaemia ( British English) is an inherited disease of the red blood cells, classified as a hemoglobinopathy (haemoglobinopathy); the genetic defect results in synthesis of an abnormal hemoglobin molecule. The blood cel appearing to have enhanced resistance to malariaMalaria ( Italian: bad air ; formerly called ague or marsh fever in English) is an infectious disease which causes about 500 million infections and 2 million deaths annually, mainly in the tropics and sub-Saharan Africa. The protozoan cause of malaria was.

Several hereditary diseases are sex-linked, meaning that they afflict one sex much more common than the other because the mutation is located on the X (or, rarely, on the Y) chromosome.

External links

• Genetic Disease Information from the Human Genome Project