Clinical Cytogenetics

Question 1

What are the two most common leukemia translocations?

Answer 1

t(9;22) for chronic lymphocytic leukemias

t(15;17) for specific acute myeloid leukemia

Question 2

What are the common cytogenetic findings in childhood B-cell leukemia and prognoses?

Answer 2

High hyper-diploidy (specifically Trisomy 4, 10, 17)

Question 3

The following FISH probes are used to monitor treatments or disease progression for what sorts of mutations?
(1) centromere (2) locus specific identifier (3) fusion

Answer 3

(cen) = enumeration

(LSI) = deletion & duplication

(F) = translocation

Question 4

What are the benefits of CMA?

Answer 4

• Detects chromosomal gains and losses
• Equivalent to performing 180,000 FISH studies at once
• Detects abnormalities in “hotspots”
• May detect abnormalities in the backbone of the genome

Question 5

What are the limitations of CMA?

Answer 5

• Can not detect balanced rearrangements
• Can not detect specific DNA mutations, single base pair changes
• May not detect low level mosaicism
• Detection of CNVs may have unclear clinical significance