Question

An individual has been referred to you with the following symptoms: They are a tall, thin male, with poorly developed male sexual characteristics, who has not been able to have children. The initial diagnosis was Klinefelter syndrome, but, although a formal karyogram has not been prepared, a quick chromosome count showed he is 46, XX.  

a.  Develop a hypothesis about the nature of the genetic cause of this individual’s symptoms.

b. What test or tests would you do to determine if your hypothesis is correct?

c. What results would you predict from your tests if your hypothesis is correct?   

d. Explain to the individual (who is not a scientist) how you will do the test(s), and how the information they would give could explain the cause of his symptoms.

Answer 1

a. There is unequal crossing over between X and Y chromosome of the father during meiosis which results in X chromosome containing SRY gene which then if pair with a X chromosome gives rise to a male with XX genotype.

b. Karyotyping can be done or FISH analysis can be done to see if the SRY gene is present.

c. That the person contains XX and not XY chromosome, SRY gene is present by FISH, location of SRY gene can be detected by fluorescent in situ hybridization.

d. Blood collected followed by subsequent tests may help the person in knowing the cause of his symptoms.