Genetics: Sickle Cell Disease

Genetics Writing Assignment
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1
* Sickle cell disease is often caused by the mutation in the HBB gene which encodes for beta-globin. In patients suffering from sickle cell disease, HBB gene mutation results in the formation of hemoglobin S (HbS) which replaces at least one beta-globin subunit. It has an autosomal recessive form of inheritance giving a 50% chance that their child would inherit/manifest with the disease. (U.S. National Library of Medicine, 2020).
* Yes. Patients with the disease often manifest with anemia, repeated infections, and periodic episodes of pain (U.S. National Library of Medicine, 2020).
* Prenatal chronic villus sampling (CVS) and amniocentesis are often performed to test for birth defects and other genetic conditions (U.S. National Library of Medicine, 2020).
2
* Down syndrome may be caused by the translocation of chromosome 21 to a different chromosome during meiosis in the parent or the early stages of fetal development.
The majority of the cases of Down syndrome are not hereditary. In trisomy 21, this chromosomal abnormality is due to a random event during meiosis in the parent. Mosaic down syndrome happens as a random event during the very early stage of cell division of fetal development. This results in some cells containing only a pair of chromosome 21 and others contain three copies of chromosome 21. (U.S. National Library of Medicine, 2020).
Since most types of down syndromes are not inherited but are just random events during meiosis and early stages of fetal development, we cannot say whether their child would develop down syndrome. The fact that Christopher’s sister had a child with downs syndrome doesn’t mean th...