Chapter 5: Clinical Cytogenetics

Chapter 5. Clinical Cytogenetics

In regards to chromosome aneuploidies in humans:

A. They are rare at the time of conception.

B. They are seen more often as pregnancy progresses.

C. If present at conception, they most often end in a miscarriage.

D. All whole chromosome trisomies are incompatible with postnatal life.

E. All whole chromosome monosomies are incompatible with postnatal life.

C is the correct answer. The other answers are incorrect because:

• A. Chromosome aneuploidies are not rare at conception. They occur in about 50% of all conceptions.

• B. Chromosome abnormalities are frequently lost as miscarriages. The numbers decrease as pregnancy progresses.

• C. Trisomy 13, 18 and 21 are compatible with post-natal life.

• D. A 45X karyotype is a human monosomy associated with Turner syndrome.

The incidence of chromosome abnormalities at the time of conception is:

A. 1/120

B. 1/75

C. 1/65

D. 1/10

E. 1/2

E is the correct answer. The other answers are incorrect because:

The incidence of chromosome abnormalities at the time of conception is 50% (1/2).

Turner Syndrome:

A. is the only whole chromosome monosomy seen in live births in humans.

B. the most common congenital heart disease is a ventricular septal defect.

C. is milder in boys.

D. girls with this condition are usually tall for age.

E. is more accurately described as Turner's syndrome.

A is the correct answer. The other answers are incorrect because:

• A. Turner syndrome is the only whole chromosome monosomy seen in live births in humans.

• B. The most common congenital heart disease in Turner syndrome is coarctation of the aorta.

• C. Turner syndrome only occurs in females.

• D. Girls with Turner syndrome condition are usually short for age.

• E. The apostrophe "s" does not go on the end of an eponym.

In regards to chromosome disorders in humans:

A. they occur rarely and are not of major clinical importance.

B. they may show a paternal age effect.

C. aneuploidies for the ...