Q: A clinical geneticist is studying a family with a rare heart disease. The gen
ID: 205083 • Letter: Q
Question
Q: A clinical geneticist is studying a family with a rare heart disease. The geneticist discovers a mutation that he believes may be the cause of the disease. However, the mutation is in a gene called mrag1 that is not expressed in the heart. The geneticist also performs an expression microarray experiment with a biopsies of heart tissue of affected and unaffected family members and discovers that a gene called het1 is expressed at much lower levels in family members with the disease compared to members who do not have the disease. In other words, individuals who have the mrag1 mutation have low expression of het1. The mrag1 gene is discovered to be about 80,000 nucleotides away from the het1 gene. How might a mutation in mrag1 lead to low expression of het1? Remember that mrag1 is not expressed in heart.
Explanation / Answer
There are some molecules which are synthesized in one type of cells and which acts on another type of cells on which they have their receptor. Most this type of molecules is called as hormones. These hormones have receptors on the effector cells. When hormones bind to the receptor they initiate a chain of cascade which leads to expression or inhibition of the molecules. In our case since there is there is the mutation in the mrag1 gene which is the hormone which under normal condition is expressed in the cell other than heart and though blood reached heart cell, where it binds to its receptor and leads to expression of het1 gene.
When mrag1 gene is mutated it can no longer binds to receptor present on the heart cell as a result of it there is low expression level of het1 gene
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