Question

At least 400 words. Our system will use turn it in to check the work, so please make sure to use your own words.

Please do not use handwriting, I always have trouble to read the handwriting

Children with DiGeorge Syndrome are born without a thymus. Discuss, in detail, the repercussions to body defense mechanisms caused by this disease.

Answer 1

It is a primary immune deficiency. It is due to the deletion in the chromosome number 22 .

Thymus is very important in the defence of the body. Primarily it helps in the maturation of the T-lymphocytes. So, lack of the thymus due to mutations, can lead to severe immunodeficiency. The size of the thymus decides the number of T cells in the blood. If the thymus gland is completely absent , T cells may be considerably very few. There will not be functional T cells circulating int he blood. T cells are very important for activation of other components of the immune system . T cells are responsible for Cell mediated immunity.

Pre mature T cells are produced by bone marrow. They are transported to Thymus gland where they complete their maturation. T cells undergo positive and negative selection to become mature cells. Positive selection is to select the T cells which bind tightly with their TCR to the MHC calss I or II. Such T cells are positively selected. Negative selection is to destroy cells that try to attack their own body proteins. So this way the thymocytes are trained to attack the foreign antigens and not self antigens.

Because fo the lack of the selection process, there will be more autoimmune diseases in a person with Digeorge disease. Most common autoimmune disease is ideopathic thrombocytopenia purpura ( plates to destroy antibodies), autoimmune hemolytic anemia, autoimmunity against joints or autoimmune arthritis, autoimmunity against thyroid gland. Thymus causes deletion of the T cells attacking the self antigen. In the absence of the thymic deletion of the cells attacking the self antigen so many autoimmune diseases are seen in such children having thymic deficiency due to mutation in the chromosome 22.