Genetic Disorders
Genetic Disorders, medical conditions caused by an error in a person’s genetic material. Some genetic disorders result in medical problems that are apparent at birth (see Birth Defects ), while other genetic disorders do not become evident until childhood or adult life. Genetic disorders range in severity from those that cause death to those that produce only mild problems, such as color blindness. Scientists have identified more than 9,000 genetic disorders. Some of these disorders are extremely rare, while others are comparatively common. Scientists have identified certain categories of genetic disorders, some of which have characteristic inheritance patterns. One category consists of single-gene disorders—disorders that involve an error in the DNA that makes up an individual gene. A second category of genetic disorders involves abnormalities of chromosomes in which too much or too little chromosomal material is present. Some genetic disorders are said to be multifactorial, because t