5. You have run across a family in which several members have developed colon ca

Question

5. You have run across a family in which several members have developed colon cancer in the 30-50 age range. You check all the known genes involved in hereditary colon cancer and find no suspicious mutations among them. You manage to piece together the health history of a number of generations in the past shown to the right. You are convinced that it is hereditary, and therefore may involve a novel gene involved in cancer You have access to the couple in the last generation of the pedigree above and their five children and three young grandchildren. Their pedigree is continued below. Man I has undergone surgery and chemotherapy and is ok for the moment, as is the case for his affected daughter. His older son's cancer was caught too late. After looking for linkage between the cancer and an assortment of markers you determine that a particular microsatellite marker seems to be linked to the disease. Below is the recent family pedigree with electrophoretic analysis of the microsatellite for each individual shown under each individual a) How does the disease appear to be inheriting? b) Which individuals are likely to get colon cancer by the age of 50? c Not all of the microsatellite results are as expected. Which ones are not, and give two different reasonable reasons why the bands are the way they are

Explanation / Answer

Ans a. The disease seems to be inherited as X linked inheritance because we can see that it is equally distributed in male and female in generation I and II. It might develop in later stage in generation III which is the feature of given disease.

b. In the pedigree the individual no. 5 of generation II and individual no. 2 of III generation are likely to develop this disease at later stage. Because they have similar band specifically present in the affected individual.

c. Microsatellites of individual 3 of III generation are not expected as it has none of the band similar to parent which is not possible.

Individual 6 also has very different microsatellites which are not the same as parent.

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