Understanding Female X Chromosome Inheritance Through Generations
written by: R. Elizabeth C. Kitchen•edited by: Leigh A. Zaykoski•updated: 2/28/2010
The X chromosome holds a great deal of ancestral genetic information. Understanding female X chromosome inheritance through generations will help you better understand the genetics of your ancestors and apply the information to your own life.
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Geneticists are finally able to study and discover the ancestral information held within the X chromosome. In order to fully understand these new discoveries, one must first understand the female X chromosome inheritance through generations. Individuals not only have some genetic material from their parents, but from many generations, such as from their grandparents and great grandparents.
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What are Chromosomes Made Of?
Each cell in the human body contains 46 chromosomes. They each follow a specific pattern and number, with 23 matching pairs. Sex is determined by the last pair. Each chromosome contains DNA, a small molecule. The molecule of DNA has genes within it that depict inherited characteristics, such as hair type, hair color, eye color, and skin color. Each individual chromosome has characteristics that distinguish it from another chromosome in location, size, dark bands, and the pattern in light.
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Inheriting the X Chromosome
Some of the genetic material that is necessary to be a female is contained within the X chromosome. Women have two X chromosomes, while men only have one X chromosome and one Y chromosome. When a female passes an X chromosome to her children, her two copies experience recombination.
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Fragile X Syndrome
If a mutation occurs during female X chromosome inheritance through generations, an inherited genetic condition called fragile X syndrome can occur. This condition occurs in every 1 in 1,600 females and is characterized by intellectual and physical features. The severity varies and females' symptoms tend to be less severe than males' symptoms. However, this condition affects more females than males.
A mutation affecting a gene on the X chromosome's long arm is responsible for causing this condition. Patients with this condition will usually have a full mutation. Those with this condition can experience intellectual impairment, connective tissue problems, long face, enlarged ears, prominent chin, and certain behavioral characteristics, such as speech disturbances, hand flapping, poor eye contact, attention deficit disorders, hand biting, autistic behaviors, and abnormal responses to various auditory, touch, or visual stimuli.
There is no cure for this disorder. Treatment involves treating the symptoms. Therapies such as special education, occupational therapy, language therapy, and behavioral therapies help people with fragile X syndrome cope with this condition. Certain medications may also be beneficial, particularly to help lessen aggression, hyperactivity, anxiety, and poor attention span. Each treatment plan will be tailored to the individual patient. This plan will be tailored after the individual is tested to determine the severity of his symptoms. There are also tests available to determine if a person has this genetic mutation and these include the Southern Blot analysis and the polymerase chain reaction analysis.
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The National Fragile X Foundation. (2010). Summary of Fragile X Syndrome. Retrieved on January 29, 2010 from The National Fragile X Foundation: http://www.fragilex.org/html/summary.htm
Genetic Science Learning Center. (2010). The Four Types of DNA. Retrieved on January 29, 2010 from the Genetic Science Learning Center: http://learn.genetics.utah.edu/
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X Chromosome Diagram: Armin Kubelbeck – Wikimedia Commons