A woman comes to your genetic counseling center because she

A woman comes to your genetic counseling center because she knows that Huntington disease occurs in members of her family. Her paternal grandfather was afflicted, but so far her father shows no symptoms. Her two great-great grandmothers on her father\'s side were healthy well into their 90s, and one of her great-great grandfathers died of unknown causes at 45. Testing for Huntington disease is extremely expensive, but she is concerned that she may fall victim to this disease and wants to plan her life accordingly. After examining her pedigree you advise her to

A. not get tested because there is no possibility that she is homozygous.

B. not get tested because only males in her family get the disease.

C. get tested because her father could be a carrier.

D. not get tested because her father is only a carrier and it is very unlikely her mother is a carrier.

E. not get tested because her 40-year-old father shows no symptoms.

Show your work.

Solution

HD is a autosomal(non sex ) dominant inherited disease which cause the death of brain cells.Adult onset is the common form.If one parent have the defective gene then the child will have a possibility of 50% to inherit the disease.

HH (MOTHER) Hh(FATHER)

normal HD

H H h (gamates)

HH (normal) Hh(HD patient)

There is no carrier in HD.This disease normally develops by 50\'s so a patient pass away by other diseases before the symptoms develop, then they might have passed the disease on.

So get tested her father could be a carrier and develop symptoms after a few years