Cancer II

Question 1

IGHG1

Answer 1

Immunoglobulin heavy chain, regulatory elements. Provides a strong, constitutive enhancer, immunoglobulin genes are strongly expressed in b-cells

Question 2

BLC6

Answer 2

proto-oncogene - a specific transcriptional repressor that inhibits the differentiation of b cells

Question 3

MYC

Answer 3

a proto-oncogene is a transcription factor that induces cell proliferation

Question 4

CCND1

Answer 4

proto-oncogene, a cell cycle regulator overexpression, which is not expressed in normal B cells

Question 5

BCL2

Answer 5

a proto-oncogene, anti-apoptotic gene

Question 6

Gene amplification is detected in two forms

Answer 6

HSRs and DMs

Question 7

HSR

Answer 7

Homogeneously staining region - duplication of chromosomal region that does not have distinguishable banding patterns

Question 8

DMs

Answer 8

Double minutes - circular extrachromosomal elements that replicate autonomously and lack a centromere and telomeres

Question 9

Amplification of MYCN gene in neuroblastoma is associated with

Answer 9

severe form of neuroblastoma with a very poor prognosis regardless of age and clinical stage. Found in about 25% of neuroblastomas.

Question 10

Trisomy 21 and leukemia

Answer 10

Individuals with DS have an increased risk of leukemia. Transient abnormal myelopoiesis (TAM) is a disorder in newborns with DS that presents with clinical and morphological findings of AML shortly after birth. Most patients exhibit spontaneous remission.

Question 11

Acquired trisomy 21 vs constitutional down syndrome

Answer 11

Acquired trisomy 21 could indicate congenital leukemia, which may require aggressive chemotherapy. Infants with down syndrome often present with transient neonatal myeloproliferation which typically resolves without treatment.

Question 12

Acute megakaryoblastic leukemia

Answer 12

approximately 30% of individuals with down syndrome will develop acute megakaryoblastic leukemia (AML-M7) before the age of 5. It is important to establish an individual’s constitutional karyotype for diagnostic and disease monitoring purposes.

Question 13

A PHA-stimulated blood chromosome study

Answer 13

since the bone marrow and blood will have a high portion of leukemic cells present, a PHA-stimulated blood chromosome study is the best test to perform. It examines t-cells to determine the patient’s constitutional karyotype.

Question 14

Which test is best to detect microdel/dup syndromes?

Answer 14

FISH

Question 15

Which gene does FISH target for DiGeorge syndrome?

Answer 15

HIRA

Question 16

Which gene does FISH target for Williams syndrome?

Answer 16

ELN

Question 17

Which gene does FISH target for Prader-Willi/Angelman syndrome?

Answer 17

SNRPN

Question 18

Which test kits does the lab use for microarrays?

Answer 18

agilent - chromosomal microarray (CMA) and illumina - single nucleotide polymorphism (SNP) microarray

Question 19

Causes of triploidy

Answer 19

1. Dispermy (double fertilization) is the principle cause, accounts for 66% of cases
2. Diploidy gametes (fertilization of a diploid ovum) that arises by occasional faults in meiosis, such as nondisjunction (10% of cases)
3. Diploid sperm (24% of cases)

Question 20

Prognosis of triploidy

Answer 20

Pure triploidy is incompatible with life and fetuses are usually spontaneously miscarried, some fetuses survive until birth but typically shortly die. Mosaic triploidy can survive longer.