Lec 10. Medical Cytogenetics Flashcards Preview

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Flashcards in Lec 10. Medical Cytogenetics Deck (30)
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1

What is the difference between constitutional and acquired cytogenetic? abnormality

Constitutional can happen before conception and a little later after fertilization. Acquired happens during teens or adulthood.

2

What are some main reasons for cytogenetic analysis?

For prenatal analysis: abnormal NIPS, old mother, fxh of chromosome abnormality, mom anxiety, abnormal ultrasound. For Postnatal analysis: multiple miscarriages. For cancer: tumors

3

What are the steps of diagnostic testing workflow?

1. pt comes and sees doc that determines what test to use. 2. Send pt to lab, draw blood etc. 3. Test sample. 4. Geneticists see results and then send to doc. 5. Pt gets results.

4

What is medical cytogenetics?

Part of clinical medicine that studies relationship between chromosomal alterations and genetic disease in humans

5

When was the cytogenetics inception?

Late 1950's

6

What did T.Painter do?

Section of human testis with spermatogonial mitosis, leading to drawing of human spermatogonial metaphase

7

What did T.S.Hsu do?

Tissue culture accidentally treated with a hypotonic solution, leading to chromosome grouping based on size and placement of centromere.

8

What are the 3 major cytogenetic methods used in clinical genetics diagnostic labs?

G-banding chromosome analysis, FISH, microarray analysis

9

What are the advantages of G-banding chromosome analysis?

1.Fast. 2. Detection of numerical abnormalities; structural chromosomal rearrangements; large depletions/duplication

10

What are the disadvantages of G-banding chromosome analysis?

Requires lots of training, minimal size of detected imbalance 5-10 mb. Low-level or tissue specific mosaisism may be missed, EPIGENETIC changes not detected. Cancer:no dividing cells = no chromosome to analyze.

11

What are the advantages of FISH?

Doesn't require dividing cells, quick screening of large number of cells, rapid results, confirmatory test to G-banding analysis, May detect mosaicisim, improved detecting of chromosomal alteration in neoplasia, can detect small deletions/duplications up to 50 kb.

12

What are the disadvantages of G-banding chromosome analysis?

Needs physician to suspect diagnosis, costly, EPIGENETIC changes not detected

13

What are the advantages of DNA Microarray?

Up to 5kb size for detection of imbalances, small amount of input DNA, comprehensive evaluations of deletions/duplications/amplifications in analysis, Mapping DNA del/dup to a specific chromosome location. Ability to determine gene content within the region of del/dup. Prior knowledge of nature of gene aberration not necessary for FISH, no requirement for tissue culture or metapahse preparation from the test specimen.

14

What are the disadvantages of DNA Microarray?

Balanced chromosomal rearrangements are not detected* challange in interretation of DNA copy number variations.

15

21 y/o F pt presents to the ED with developmental delay, sleep disturbance, self-injury behavior, speech delays, deep hoarse voice, you suspects smith Magenis syndrome. Which of the 3 tests do you order?

G-banding chromosome analysis

16

21 y/o F pt presents to the ED with developmental delay, sleep disturbance, self-injury behavior, speech delays, deep hoarse voice, you suspects smith Magenis syndrome. What is wrong with their chromosome?

Part deletion of chrom 17. 46,XX.

17

29 y/o pregnant F pt presents to the ED with 19 week ultrasound: cystic hygroma of the fetus. Which of the three tests do you order?

G-banding chromosomal analysis

18

29 y/o pregnant F pt presents to the ED with 19 week ultrasound: cystic hygroma of the fetus. What is wrong with the babies chromsome and what disease is it?

Missing an X chromosome 45,X. Turner syndrome

19

25 y/o old pregnant female presents to the ED with the babies abnormal NIPS ans ultrasound at 20 weeks showing unilateral cleft lip, single umbilical artery, choroid plexus cyst, skull abnormality. Which of the three tests do you order?

FISH

20

25 y/o old pregnant(1st) female presents to the ED with the babies abnormal NIPS ans ultrasound at 20 weeks showing unilateral cleft lip, single umbilical artery, choroid plexus cyst, skull abnormality. What is wrong with their chromosome and what disease do they have?

Extra copy of chrom 18. Trisomy 18.

21

21 y/o pregnant(2nd) f presents to the ED with ultrasound abnormalities: large cystic hygroma, massive skin edema. Which of the 3 tests do you order?

FISH and G-Band chromosomal analysis

22

21 y/o pregnant(2nd) f presents to the ED with ultrasound abnormalities: large cystic hygroma, massive skin edema. what do the results show?

on FISH nothing can be seen but on g-banding we can see there is a deletion on chrom 18

23

10 y/o female presents to the ED with developmental and speech delay, ataxia, recurrent seizures, microcephaly, frequent laughter and hand-clapping. Which of the three tests do you order?

Microarray analysis

24

10 y/o female presents to the ED with developmental and speech delay, ataxia, recurrent seizures, microcephaly, frequent laughter and hand-clapping. What is wrong with their chromosome? What is the disease?

Chromosome 15 has deletion, Angel-man syndrome

25

newbornd female presents to the ED with overgrowth, macroglossia, ompgalocele, which of the three tests do you order?

Microarray analysis

26

Newborn female presents to the ED with overgrowth, macroglossia, ompgalocele. What is wrong with their chromosome and what disease do they have?

UPD on chrom 11, Beckwith-widemann syndrome (imprinting syndrome)

27

65 y/o presents to the ED with constant fatigue, PE reveals enlarged spleen, blood count shows elevated white blood count. Which of the 3 tests do you order?

FISH and g-banding chromosomal analysis

28

65 y/o presents to the ED with constant fatigue, PE reveals enlarged spleen, blood count shows elevated white blood count. What does g-banding and FISH show about their chromosomes? What is the disease? Can it be treated?

G-banding shows translocation of the chrom 22 onto chrom 9. Fish confirms it. The disease is CML. Can be treated with Gleevac

29

6 day y/o m presents to the ED with persistant hypoxia, blueberry muffin skin lesions, blood count shows anemia and thrombocytopenia. Which of the 3 tests do you order?

Microarray

30

6 day y/o m presents to the ED with persistant hypoxia, blueberry muffin skin lesions, blood count shows anemia and thrombocytopenia. What is wrong with their chromosome? What is the diagnosis?

Deletion on chromo 11. Epsilon-gamma-delta-beta thalassemia