ANEUPLOIDY TESTING USING STRs

Question 1

parental testing

Answer 1

1. testing for diseases or conditions in a fetus before it is born
2. the main goal is to perform prenatal diagnostic testing at the earliest possible gestation

Question 2

types of prenatal tests - chorionic villus sampling

Answer 2

1. 11-14 weeks gestation

2. cells from chorionic villi of the placenta

Question 3

types of prenatal tests- amniocentesis

Answer 3

1. 18-23 weeks

2. fetal cells in amniotic fluid

Question 4

aneuploidy

Answer 4

1. loss/gain of one chromosome from a homologous pair

2. caused by non-disjunction

Question 5

aneuploidy- monosomy

Answer 5

1. missing one of the chromosomes of a pair
2. 45,X
3. turner syndrome

Question 6

aneuploidy- trisomy

Answer 6

1. having more than two pairs of chromosomes
2. 47,XY or XX+21
3. down syndrome

Question 7

aneuploidy detecting technique= karyotype

Answer 7

1. cell culture and harvesting
2. chromosome standing and banding
3. takes 2-3 weeks
4. expensive and time-consuming
5. gold standard

Question 8

aneuploidy detecting technique= QF-PCR

Answer 8

1. use fluorescent dye-labeled primers
2. target specific short tandem repeats
3. amplify the STRs via PCR
4. capillary electrophoresis
5. takes 2-3 days

Question 9

short tandem repeats

Answer 9

1. also called microsatellites
2. repeats are from 2 to about 9
3. STR loci account for +/- 3% of the human genome
4. most STRs are found in non-coding regions of genes but +/- are located in coding regions
5. in humans, chromosome 19 has the highest density of STRs
6. the most common STRs in humans are A-rich

Question 10

typing STRs

Answer 10

1. primers are designed to flank the STRs
2. primers for different STR loci are labeled with different colored dyes.
3. PCR amplification generates products that differ in length depending on the number of repeats

Question 11

The naming of STRs = D3S1266

Answer 11

D= DNA
3= chromosome 3
s=STR
1266= unique identifier

Question 12

aneuploidy kits = process

Answer 12

1. collect sample= blood, CVS, amniocentesis
2. extract DNA
3. amplify DNA- QF-PCR
4. perform capillary electrophoresis = using a genetic analyzer
5. electropherogram= analyze and interpret data

Question 13

electropherogram identification= normal diploid sample

Answer 13

two peaks in a 1:1 ratio

Question 14

trisomic triallelic

Answer 14

three-peak pattern
1:1:1 peak ratio
Tri21

Question 15

trisomic diallelic

Answer 15

two unbalanced peaks
2:1 peak ratio
Tri21

Question 16

AMEL

Answer 16

1:1 ratio for males because there is equal no. X and Y

for females, there will be 1 peak

Question 17

SRY

Answer 17

XY

not present for females

Question 18

chromosome 13

Answer 18

normal diploid number 1:1