Cancer cytogenetics & Chromosome instability syndromes

Question 1

What is the main cause of most chromosome abnormality syndromes?

Answer 1

Errors in the meiotic process leading to gamete formation.

Question 2

What are chromosome rearrangements in somatic cells responsible for?

Answer 2

A number of important cancers in humans.

Question 3

What is the Philadelphia chromosome?

Answer 3

A reciprocal translocation between chromosomes 9 and 22.

Question 4

What does the Philadelphia chromosome consist of?

Answer 4

Translocation of most of chromosome 22 onto the long arm of chromosome 9.

Question 5

What gene is moved due to the Philadelphia chromosome translocation?

Answer 5

ABL proto-oncogene.

Question 6

What is the effect of the ABL gene product alteration in CML?

Answer 6

Increased tyrosine kinase activity leading to malignancy in hematopoietic cells.

Question 7

What type of drugs have been developed for CML?

Answer 7

Drugs that inhibit the tyrosine kinase encoded by the ABL gene.

Question 8

How many different rearrangements have been observed in cancers?

Answer 8

More than 100 different rearrangements.

Question 9

What is the significance of identifying chromosome rearrangements in cancer?

Answer 9

Leads to a more accurate prognosis and better therapy.

Question 10

What is a routine part of the diagnosis for leukemia patients?

Answer 10

Cytogenetic evaluation of bone marrow cells.

Question 11

List some indications for performing chromosome analysis.

Answer 11

• Suspected recognizable chromosome syndrome (e.g., Down syndrome)
• Unrecognizable pattern of two or more malformations
• Ambiguous genitalia
• Intellectual disability or developmental delay
• Parents and children of persons with chromosomal translocations, deletions, or duplications
• Stillborn infants with malformation or unexplained fetal death
• Females with proportionate short stature and primary amenorrhea
• Males with small testes or significant gynecomastia.

Question 12

Define chromosome instability syndromes.

Answer 12

Autosomal recessive disease conditions exhibiting increased incidence of chromosome breaks.

Question 13

List some examples of chromosome instability syndromes.

Answer 13

• Ataxia–telangiectasia
• Bloom syndrome
• Fanconi anemia
• Xeroderma pigmentosum.

Question 14

What is a consequence of chromosome instability syndromes?

Answer 14

Increased risk of malignancy.

Question 15

What do chromosome instability syndromes result from?

Answer 15

Faulty DNA replication or repair.