Cytogenetics 1/2/3/ and cancer cyto

Question 1

substance during preparation for cytogenetics

added to promote cell division

Answer 1

PHA

Phytohemaglutinin

Question 2

female meiosis begins

Answer 2

3rd month of gestation

Question 3

phase of female meiosis , right before birth

until puberty

Answer 3

Prophase I (dictyotene)

Question 4

phase of female meiosis

after ovulation

Answer 4

Metaphase II

Question 5

Female meiosis is completed

after

Answer 5

Fertilization

Question 6

When is the 1st polar body of female meiosis formed

Answer 6

Before metaphase II

Question 7

any abnormality that is not a multiple of 23

Answer 7

Aneuploidy

Question 8

what are two main mechanisms of aneuploidy

Answer 8

1. Non-disjunction
2. Anaphase lag

Question 9

Most triplodies originate during oogenesis except for ____ which is equally likly to arise during oogenesis or spermatogenesis

Answer 9

XXY

Question 10

trisomy most likly to be a meiosis II error

Answer 10

trisomy 18

however most trisomies are M1 errors

Question 11

monosomy X is more likly to be _______ in origin

Answer 11

paternal (70%)

maternal (30%)

Question 12

male nondisjunction in meiosis II most likly to form this aneuploidy

Answer 12

XYY

Question 13

Percentage of Down syndrome that is Robersonian translocations and recurrance risk?

• Father
• Mother
• t(21;21)

Answer 13

4% Robersonian translocations (usually 14:21)

• Father with t(14;21) - 1%
• Mother with t(14;21)- 10-15%
• Etheir parent with t(21;21) - 100

Question 14

developmental delay

high hairline

diaphragmatic hernia

seizures

sparse hair, large mouth

normal karyotype

Answer 14

tetrasomy 12p

Pallister-Killian

Isochromosome 12p

tissue specific mosaicism

must do skin biopsy or microarray

Question 15

generally the tissue from which CVS karyotype is obtained

Answer 15

Inner mesenchymal core

Question 16

Most common autosomal trisomy associated with spontaneous abortions

Answer 16

Trisomy 16 (30%)

followed by 22 and 21

Question 17

single most common chromosomal abnormality in spontaneous abortions

Answer 17

monosomy X

Question 18

Risk associated with complete molar pregnancies

46 XX (90%)

Answer 18

Malignancy (Choriocarcinoma)

1-2% risk of recurrance

Question 19

number of barr bodies found in a XXY male

Answer 19

1 barr body

of barr bodies = number of X chromosomes -1

Question 20

chromosomal location of XIST/XIC

Answer 20

Xq13

Question 21

what is the product of XIST

Answer 21

produces a non-coding RNA

that coats the inactive X to inactivate it

Question 22

percentatge of genes that usually excape inactivation on X chromsome

Answer 22

10-15% total

30% on short arm Xp

3% on the long arm Xq

**Multiple copies of short arm more likly to produce an abnormal phenotype than multiples of the long arm

Question 23

which turner syndrome karyotype would be expected to have a more severe phenotype

46,X,r(X) - large ring

46,X,r(X) - small ring

Answer 23

46,X,r(X)

small ring less likly to contain XIST

therefore functional disomy of portions of X chromosomes

genes that are usually inactivated

Question 24

Most common robersonian translocation

Answer 24

t (13;14)

Question 25

draw germ cells that can be formed from a 45,XY,t (13;14) Alternate Adjacent 3:1

Answer 25

Question 26

how do you determine whether an unbalanced translocation underwent adjacent 1 or adjacent 2 during gamate formation

Answer 26

Adjacent 1 **each pole gets a normal chromosome and the opposite translocated chromosome** **partial monosomies and trisomies** Adjacent 2 **each pole gets both the normal and translocated of the same chromosome** **rare**

Question 27

for duplication \_\_\_\_\_\_\_\_analysis is preferred for visualization of tandem duplications for deletions ________ is prefered

Answer 27

interphase metaphase

Question 28

prenatal aneuploid screen probes target the centromeres of \_\_\_,\_\_\_,\_\_\_ cetromeric probes are not specific to \_\_\_,\_\_\_ so must use locus specific probes

Answer 28

18,X,Y, 13,21

Question 29

\_\_\_ ___ FISH strategy used for loci which rearrange with multiple partners

Answer 29

"break apart"

Question 30

FISH probe cocktail for detection of del 22q11.2

Answer 30

22q11.2 LSI *TUPLE 1* 22q13 LSI *ARSA*

Question 31

Philidelphia chromosome

Answer 31

der (22) CML- tramslocation 9;22 beakpoint on chromosome 9 is constant

Question 32

creation of more chromosomal abnormalities in a tumor

Answer 32

clonal evolution

Question 33

BCR-ABL found using _________ probe

Answer 33

dual-fusion

Question 34

treatment used for myelodysplasitic syndrome PML/RARA t(15;17)

Answer 34

ATRA (all-trans retinoic acid)

Question 35

progressive ataxia oculocutaneous telangiectasia immune deficiency chromosome instability when exposed to xray increased AFP

Answer 35

Ataxia telangiectasia *ATM* (loss of function mutation) can have positive newborn screen for TREC (immune deficiency)

Question 36

butterfly rash growth deficiency immune defects increase sister chromatid exchange

Answer 36

Bloom Syndrome BLM RecQ helicase

Question 37

cardiac, renal, limb anomalies progressive bone marrow failure radial ray anomalies "VACTRL" increase chromosome breakage

Answer 37

Fanconi Anaemia * FANC-A* (60-70%) * FANC-C* : most common in AJ pop. testing of lymphocytes with diepoxybutane (DEB) and mitomycin C (MMC) *BRCA1* and *BRCA2* are part of the FANC pathway