DIRAS3 is a paternally expressed and maternally imprinted gene located on chromosome 1 in humans. Reduced DIRAS3 expression is linked to an increased risk of breast and ovarian cancers the protein encoded by DIRAS3 is not expressed, suggesting that it functions as a tumor suppressor gene. The protein it codes for, ARHI, influences the cell cycle. Specifically
ARHI's strong inhibition of the cyclin D1 promoter.
a. Assume the couple below is totally healthy but has 3 children, 2 of which have developed cancer
by the age of 27.
Fill in the probable genotypes of the parents below.
b. Identify what percentage of their children are likely to get cancer.
c. How would the above results be different if the genotypes were reversed?
d. now, explain why DIRAS3 mutations are likely to cause cancer