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Page | Case It! Home Page | WSC Biology Department |
INTRODUCTION
Sicle cell anemia is a desease of the red blood cells. It is caused by a mutation in the hemoglobin gene.A single base change results in a single amino acid substitution. This mutataion causes the hemoglobin to change its conformation to a more elongated form under certain conditions, distorting the red blood cells and impairing their ability to carry oxygen. Sickle cell anemia is considered a recessive trait, since both chromosomes have to carry the mutation in order for the full blown disease symptoms to appear.:
MOLECULAR BIOLOGY OF
THE DISEASE
The molecular biology of Sicle Cell Anemia has recently been unraveled by Alan Bethea and Rob Brenckman These two rocket scientists isolated total DNA from the nasal scrapings of a person exhibiting Sickle Cell Anemia and amplified the Sickle Cell sequence using PCR. A special stain was applied to the gel and a peculiar pattern was observed (see Figure 1 below).
There is no known medical cure.
The predictions for the future are uncertain.
LAB PROCEDURE AND
GEL/BLOT INTERPRETATION
DNA from two parents who are carriers of Sickle Cell Anemia is isolated and amplified using PCR and the Sickle Cell primers. The samples are then applied to a gell and stimulated with an electrical charge to separate the varying lengths of the tested samples. The samples are then compared to find coresponding traits.
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| Figure 1. PCR amplified DNA from a both parents who are carriers (Lane 2 father, Lane 4 mother.) Both parents results show the recessive trait (left marker.) |
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| Figure 2. PCR amplified DNA from the daughter (Lane 1) and the fetus (Lane 2). The daughters sample shows no sign of the ressessive trait but the fetus shows full inheritance of the disorder. |
STATEMENT TO
FAMILY
Dear Mr. and Mrs. whoever, we regret to inform you that you are both carriers of the Sickle Cell disorder. Although your first child shows no signs of carrying this recessive disorder, extensive tests have revealed that your unborn fetus is afflicted with the disorder. Upon delivery your newborn will be screened again and at that point appropriate measures and plans will be made to help your newborn and your family deal with this disorder.
If you think or know that a family member is a carrier of or has Sickle Cell Anemia, you should promptly seek medical attention. Due to the hereditary nature of this disorder it is important that you do not sexually reproduce. Please have yourself checked if there is any evidence of this disorder in your family history.
There is no known cure so please reproduce with caution
Yours truly
Dr.Tact
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