Diseases: Sex Linked and Sex Influenced
Diseases: Sex Linked and Sex Influenced
by Richard Nixon
Honors Biology
Mrs. Linda
December 19, 1994
There are thousands of cases of sex linked and sex influenced diseases worldwide. These diseases can range from a social inconvenience, to a fatal ailment. In sex linked diseases, like Muscular Dystrophy, hemophilia and color blindness, only males are affected. When a man infected with a sex linked disease has children, all his sons are normal, but all of his daughters are carriers. When a carrier woman and an uninfected man have children, half of the sons are normal, and half of the sons are affected; half of the daughters are carriers and half of the daughters are normal. Only males are affected because the sex linked diseases affect the X chromosome. Males have one X chromosome and one Y chromosome, so they need to use that X, whether it is flawed or not.
Females on the other hand, have two X chromosomes, so if one is defective, they can use their second X chromosome. Duchenne's Muscular Dystrophy(DMD) is defined as "a genetic disease characterized by defective muscle cells that can not produce a protein called dystrophins (Science News 380). In patients of hemophilia, there is a deficiency of a protein needed for blood clotting, causing this hereditary bleeding disorder. In red/green color blindness, the broadest form of color blindness that affects six percent of the population, the cones in the retina that receive green light do not function properly. Unlike sex linked diseases, sex influenced diseases are not reserved solely for the male. However, the diseases occur in males much more frequently than in females.
This is because sex influenced diseases occur from imbalances in testosterone, much more highly concentrated in males. Baldness and gout are two diseases that are a result of these hormonal imbalances. Baldness is defined as the lack or loss of hair. Permanent baldness strikes on a hereditary basis because the hormonal imbalances
by Richard Nixon
Honors Biology
Mrs. Linda
December 19, 1994
There are thousands of cases of sex linked and sex influenced diseases worldwide. These diseases can range from a social inconvenience, to a fatal ailment. In sex linked diseases, like Muscular Dystrophy, hemophilia and color blindness, only males are affected. When a man infected with a sex linked disease has children, all his sons are normal, but all of his daughters are carriers. When a carrier woman and an uninfected man have children, half of the sons are normal, and half of the sons are affected; half of the daughters are carriers and half of the daughters are normal. Only males are affected because the sex linked diseases affect the X chromosome. Males have one X chromosome and one Y chromosome, so they need to use that X, whether it is flawed or not.
Females on the other hand, have two X chromosomes, so if one is defective, they can use their second X chromosome. Duchenne's Muscular Dystrophy(DMD) is defined as "a genetic disease characterized by defective muscle cells that can not produce a protein called dystrophins (Science News 380). In patients of hemophilia, there is a deficiency of a protein needed for blood clotting, causing this hereditary bleeding disorder. In red/green color blindness, the broadest form of color blindness that affects six percent of the population, the cones in the retina that receive green light do not function properly. Unlike sex linked diseases, sex influenced diseases are not reserved solely for the male. However, the diseases occur in males much more frequently than in females.
This is because sex influenced diseases occur from imbalances in testosterone, much more highly concentrated in males. Baldness and gout are two diseases that are a result of these hormonal imbalances. Baldness is defined as the lack or loss of hair. Permanent baldness strikes on a hereditary basis because the hormonal imbalances
Cited: "Color Blindness Misconceptions." USA Today 120 (1992):16 "Foot Feat: transplant treats dystrophy." Science News 16 June 1990:380 Grady, Denise. "One foot forward." Discover September 1990:86-93 Massie, Robert., and Massie, Suzanne. Journey. New York: Alfred A. Knopf, 1961. Norton, Peter B. "baldness." The New Encyclopedia Britannica. 1994 ed. Norton, Peter B. "gout." The New Encyclopedia Britannica. 1994 ed. Norton, Peter B. "hemophilia." The New Encyclopedia Britannica. 1994 ed. Thompson, Larry. "Cell transplant results under fire." Science 257 (24 July 1992) 472-474