Question

How is sickle cell anemia an example of a pleiotropy?

Answer 1

I think this link could explain it better...
http://www.bookrags.com/research/pleiotropy-gen-03/

Answer 2

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1470873/pdf/15166132.pdf

Answer 3

"The allele responsible for sickle-cell anaemia is autosomal recessive and can be found on the short arm of chromosome 11. A person who receives the defective gene from both father and mother develops the disease; a person who receives one defective and one healthy allele remains healthy, but can pass on the disease and is known as a carrier. If two parents who are carriers have a child, there is a 1-in-4 chance of their child developing the illness and a 1-in-2 chance of their child just being a carrier. Since the gene is incompletely recessive, carriers have a few sickle red blood cells at all times, not enough to cause symptoms, but enough to give resistance to malaria. Because of this, heterozygotes have a higher fitness than either of the homozygotes. This is known as heterozygote advantage.