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Genetic Disorders Genetic disorders Genetic disorders are conditions that have some origin in an individual's genetic make-up. Many of these disorders are inherited and are governed by the same genetic rules that determine dimples and red hair.
However, some genetic disorders—such as Down syndrome, characterized by heart malformation, poor muscle tone, and a flattened face—result from a spontaneous mutation gene change that takes place during embryonic earliest life development.
Genetic disorders can be classified according to the way in which they develop. If the disorder is transmitted by genes inherited from only one parent, it is said to be an autosomal dominant disorder.
The term autosome applies to any of the 22 chromosomes that are identical in human males and females. Chromosomes are structures that organize genetic information in the nucleus of cells.
By contrast, disorders that can be inherited only by the transmission of genes from both parents is called an autosomal recessive disorder.
Other genetic disorders are associated with the X female or Y male chromosome and are called sex-linked disorders because the X and Y chromosomes are related to sexual characteristics in humans.
Finally, the development of some genetic disorders involves environmental factors, factors present outside the organism itself. Such disorders are known as multifactorial genetic disorders.
Principles of genetic inheritance Genetic information in humans is stored in units known as genes located on large complex molecules called chromosomes. A vast range of human characteristics, from eye and hair color to musical and literary talents, are controlled by genes.
To say that a person has red hair color, for example, is simply to say that that person's body contains genes that tell hair cells how to make red hair.
Reproduction in humans occurs when a sperm cell from a male penetrates and fertilizes an egg cell from a female. The fertilized egg cell, called a zygote, contains genes from both parents.
For example, the zygote will contain two genes that control hair color, one gene from the mother and one gene from the father. In some cases, both genes carry the same message.
For example, the zygote might contain two genes that act as a kind of code that tells a cell to make red hair, one from each parent. In that case, the child will be born with red hair.
Words to Know Chromosomes: Structures that organize genetic information in the nucleus of cells. A trait that can manifest be expressed when inherited from one parent.
A section of a chromosome that carries instructions for the formation, functioning, and transmission of specific traits from one generation to another.
A trait that results from both genetic and environmental influences. Large molecules that are essential to the structure and functioning of all living cells.
A trait that is expressed in offspring only when identical genes for the trait are inherited from both parents. A disorder that generally affects only one sex male or female. In other cases, two genes may carry different messages.
The zygote might, for instance, carry a gene for red hair from the mother and for brown hair from the father. In such cases, one gene is dominant and the other recessive. As these terms suggest, one gene will "win out" over the other and determine the offspring's hair color.
In this example, the gene for brown hair is dominant over the gene for red hair, and the offspring will have brown hair. Dominant genetic disorders If one parent has an autosomal dominant disorder, then offspring have a 50 percent chance of inheriting that disease.
Approximately 2, autosomal dominant disorders ADDs have been identified. These disorders have effects that range from inconvenience to death.African Americans, more than other ethnic groups, can inherit a 6th finger. In most cases, this is not caused by a genetic disease.
Polydactyly can also occur with some genetic diseases. Extra digits may be poorly developed and attached by a small stalk. This most often occurs on the little finger side of the hand.
Footnotes * Medically necessary if results of the adrenocortical profile following cosyntropin stimulation test are equivocal or for purposes of genetic counseling.. Footnotes ** Electrophoresis is the appropriate initial laboratory test for individuals judged to be at-risk for a hemoglobin disorder..
In the absence of specific information regarding advances in the knowledge of mutation. May 08, · Polydactyly is a condition in which a person has more than five fingers per hand or five toes per foot. It is the most common birth defect of the hand and foot.
Polydactyly can occur as an isolated finding such that the person has no other physical anomalies or intellectual impairment. GENETIC ANOMALIES OF CATS , Sarah Hartwell.
The following categories of defect are frequently used to describe feline genetic anomalies. Short-rib thoracic dysplasia (SRTD) with or without polydactyly refers to a group of autosomal recessive skeletal ciliopathies that are characterized by a constricted thoracic cage, short ribs, shortened tubular bones, and a 'trident' appearance of the acetabular roof.
Hereditary multiple osteochondromas (HMO) also known as Hereditary multiple exostoses is a disorder characterized by the development of multiple benign osteocartilaginous masses in relation to the ends of long bones of the lower limbs such as the femurs and tibias and of the upper limbs such as the humeri and forearm urbanagricultureinitiative.com are also known as osteochondromas.