Sickle Cell Disease

Hemoglobin

Protein made of many amino acids The sequence of amino acids is

genetic coded by DNA Function to carry oxygen and other

compounds

Genetic Process

DNA contains compounds called bases– adenine, thymine, guanine and cytosine– in a genetic coded sequence

mRNA– matches up to those bases and reads the message– where an adenine/thymine, guanine/uracil etc

Moves to cytoplasm of cell and waits for t-RNA carrying the amino acid to find the right sequence and drop off its amino acid

www.vcbio.science.ru.nl/ images/cellcycle/mcel...

http://fig.cox.miami.edu/~cmallery/150/chemistry/hemoglobin.jpg

Normal Pathology

Inherit 2 copies of the gene called Alleles

When born have Hemoglobin F By 3 months replaced by Hemoglobin

A

Sickle Cell

Caused by a SNP– single nucleotide polymorphism

DNA has Adenine (A base) replaced by Thymine (T base)

So Code is GTG instead of GAG Valine get put in place of Glutamic acid

in 6th amino acid of both beta chains

Sickle Cell continued

Under certain conditions such as low O2 , the hemoglobin molecules stick together or polymerize

Stretches the Red Blood Cells to look like a “sickle”

Affects about 8-11% of African Americans

http://www.healthsystem.virginia.edu/internet/hematology/HessImages/Sickle-Cell-Disease-40x-website.jpg

Problems

Cells can’t move thru microvessels Blood get thick or viscous Spleen removes the defective cells Stroke Infections Difficulty breathing Pain Organ failure or damage

Treatment Antibiotics started very early in children Transfusions Drugs to Aid in production of Hemoglobin F

Hydroxyurea Butyrate

IV dose and oral 30-40 tablets per day Pulse therapy

Bone Marrow Transplantation