Question 1

Which of the following techniques is most commonly used to visualize and identify individual chromosomes based on their banding patterns?

Accepted Answer

Giemsa (G) banding

Question 2

A karyotype is a display of chromosomes arranged according to which characteristic?

Accepted Answer

Length

Question 3

Which chromosomal abnormality is most frequently observed in live births?

Accepted Answer

Trisomy 21

Question 4

A patient’s karyotype is described as 46,XY,del(4)(p14). What does this indicate?

Accepted Answer

Male with deletion of the distal part of the short arm of chromosome 4

Question 5

Which of the following statements about trisomy 21 (Down syndrome) is correct?

Accepted Answer

It is the most common autosomal aneuploidy among live births

Question 6

What is the most likely mechanism leading to mosaicism in an individual with trisomy 21?

Accepted Answer

Nondisjunction during mitosis in early embryonic development

Question 7

Which of the following is a balanced chromosomal rearrangement?

Accepted Answer

Reciprocal translocation

Question 8

A Robertsonian translocation most commonly involves which group of chromosomes?

Accepted Answer

Acrocentric chromosomes (13, 14, 15, 21, 22)

Question 9

Which of the following karyotype notations describes a female with duplication of the short arm of chromosome 5?

Accepted Answer

46,XX,dup(5p)

Question 10

Which of the following is true regarding the gene-dosage hypothesis in trisomy 21?

Accepted Answer

Clinical symptoms are due to the presence of an extra copy of chromosome 21 and overexpression of its genes

Question 11

Which of the following is a feature of Patau syndrome (trisomy 13)?

Accepted Answer

Holoprosencephaly

Question 12

Which chromosomal abnormality is most likely to be lethal when present in all cells of an individual?

Accepted Answer

Monosomy of an autosome

Question 13

Which of the following best describes polyploidy?

Accepted Answer

Any multiple of the basic haploid chromosome number other than the diploid number

Question 14

Which method is most suitable for detecting small chromosomal rearrangements such as microdeletions?

Accepted Answer

FISH (fluorescence in situ hybridization)

Question 15

A child is born with a karyotype 47,XX,+21. What is the most likely clinical diagnosis?

Accepted Answer

Down syndrome

Question 16

Which of the following is a consequence of anaphase lag during cell division?

Accepted Answer

Loss of a chromosome from one daughter cell

Question 17

Which of the following statements about autosomal trisomies is correct?

Accepted Answer

Trisomy 21, 13, and 18 are the only autosomal trisomies compatible with survival until birth

Question 18

Which of the following is a feature of mixoploidy?

Accepted Answer

Presence of two or more genetically different cell lines derived from a single zygote

Question 19

Which of the following is true regarding the relationship between maternal age and the incidence of trisomy 21?

Accepted Answer

Incidence of trisomy 21 increases with maternal age due to increased nondisjunction

Question 20

Which of the following is a characteristic of balanced chromosomal rearrangements?

Accepted Answer

They often do not produce serious health consequences in the individual but can affect offspring

Clinical Cytogenetics: Autosomal Chromosome Abnormalities – Study Notes

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