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'''Sickle cell disease''' ('''sickle cell anemia''') is a genetic blood disease seen most commonly in people of [[Africa]]n ancestry. Sufferers are chronically [[anemic]] and experience significant damage to their heart, lungs, and kidneys. Cells affected by the disease take on a sickle shape (that is, shaped like a "C").
Normal red [[blood]] cells are smooth and round like a doughnut without a hole. They move easily through [[blood vessel]]s to carry oxygen to all parts of the body. Sickle-shaped cells don't move easily through blood. They're stiff and sticky and tend to form clumps and get stuck in blood vessels.
The clumps of sickle cells block blood flow in the blood vessels that lead to the limbs and organs. Blocked blood vessels can cause pain, serious infections, and organ damage.
==Cause==
The disorder is caused by a genetic defect which causes the blood protein [[hemoglobin]] to form improperly, making it difficult for [[oxygen]] to join with it and be carried through the blood from the lungs to other parts of the body. The specific cause is when the [[gene]] which creates hemoglobin has a single [[base pair]] change, which causes individual hemoglobin proteins to clump together, impairing [[oxidation]].
As a result of this [[mutation]], the [[red blood cell]]s tend to take on a sickle shape, rather than their characteristic donut shape.
Sickle cell disease in a child is determined by inheriting two recessive [[allele]]s from the parents which code for hemoglobin. If a person inherits one [[dominant]] and one [[recessive]] allele (i.e., he is [[heterozygous]]), he is not affected by the disease, but rather benefits from a [[resistance]] to [[malaria]]. Inheritance of two dominant alleles, of course, causes neither the disease nor any resistance to malaria.
== Sources ==
* [http://www.genome.gov/glossary.cfm?key=sickle%20cell%20disease Genome.gov]
* [http://www.nhlbi.nih.gov/health/dci/Browse/Blood.html NIH Glossary]
[[Category:Diseases]]