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    How Much Do You Know About Genetic Inheritance?

    Most of us studied the basics of dominant and recessive genes at some point. However, genetics are much more complicated than this. How far beyond the basics does your knowledge go?


    Huntington's Disease is a progressive neurological condition with a dominant inheritance pattern. What causes the defective version of this gene to cause disease?


    Hemophilia is a genetic flaw in the production of a protein needed for blood to clot. It affects almost exclusively boys. Why can we say with confidence that a child has no risk of inheriting this condition from a healthy father, but usually inherits it from a healthy mother?


    Rett's syndrome is a genetic condition that causes apparently normal infants to undergo rapid neurological regression and develop unusual behaviors and physical symptoms. It normally affects exclusively girls. How does this work?


    Angelman's syndrome causes severe intellectual disabilities and unusual behavior known as "happy puppet" syndrome. Prader-Willi syndrome causes mild to moderate intellectual delay, distinctive appearance, and an incessant need to eat, causing morbid obesity. Both genes are located on chromosome 15. How else are they related?


    Sonic Hedgehog is a gene critical to development of the fetus. Among other things, it dictates the width of the face, the division of the brain into hemispheres, and the development of limbs. Defects in Sonic Hedgehog can cause severe abnormalities or almost no abnormalities in individuals in the same family. How does this work?


    Trisomy 21, otherwise known as Down Syndrome, occurs when an individual has three copies of chromosome 21. Affected individuals have developmental delays and are prone to heart defects and other health problems, although some of them function very well in structured environments. Trisomy 21 is the most common trisomy diagnosed in newborns. Why is it so common?


    Sickle cell anemia is a recessive condition in which individuals with two defective genes have red blood cells that "sickle" or change shape when deprived of oxygen, causing damage to blood vessels and organs. Although it is a serious condition and it can be deadly, it is an unusually common condition, especially in people whose ancestors came from particular areas of the world. Why hasn't this condition been eliminated by evolution if it is so harmful?