QF-PCR Aneuploidy Testing

Question 1

the gain or loss of a chromosome

Answer 1

aneuploidy

Question 2

define non-disjunction

Answer 2

failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually = abnormal distribution of chromosomes in the daughter nuclei

Question 3

Turner Syndrome

Answer 3

Monosomy X; 45,X
- usually paternal non-disjunc
- short stature, webbed neck, low hairline, normal intelligence, loss of ovarian function, cardiac defects and kidney disease

Question 4

frequency of Turner Syndrome

Answer 4

1 in 2500 newborn girls worldwide

Question 5

Klinefelter syndrome

Answer 5

47, XXY
- paternal or maternal non-disj
- tall with long limbs
- small testes, penis, breast growth, decrease sexual interest, lower than ave intelligence

Question 6

Trisomy X

Answer 6

47, XXX
- most common female sex chromosome aneuploidy
- maternal non-disj
- taller than average, developmental delays

Question 7

XYY syndrome

Answer 7

Jacob’s syndrome; 47 XYY
- paternal non-disj or post-zygotic cleavage errors
- tall, enlarged head, anti-social, learning disabilities, usually fertile
- 1 in 1000 live male births

Question 8

Patau syndrome

Answer 8

Trisomy 13; somatic; 47, XX or XY+13
- non disj of either parent
- small eyes, extr digits, cleft palate, hart and CNS defects
- 90% infants die within a year

Question 9

diagnosis for Patau syndrome

Answer 9

quad test
- low free estriol
- low AFP
- low inhibin A
- low B-HCG

Question 10

central walls of heart not formed

Answer 10

Patau

Question 11

clenched fists

Answer 11

Patau

Question 12

Edwards Syndrome

Answer 12

Trisomy 18; 47, XX or XY+18
- maternal non-disj usually
- small, long head, small mouth, underweight, feeding and breathing problems, heart and genitourinary issues
- severe cognitive impairment
- freq increases with maternal age
- 90% infants die within a year

Question 13

overlapping fingers

Answer 13

Edwards

Question 14

clubfeet

Answer 14

Edwards

Question 15

Downs Syndrome

Answer 15

Trisomy 21; 47, XY or XX+21
- majority maternal non-disj
- craniofacial abnormalities, heart defect, childhood leukemia, early-onset Alzheimer’s, mild to moderate cognitive impairment
- freq increases with maternal age

Question 16

short tandem repeats (STRs) aka

Answer 16

microsatellites
- type of variable number tandem repeat (VNTR)

Question 17

define STRs

Answer 17

short nucleotide sequences of 2 or 6 nucleotides that repeat multiple times
- ex: D8S1179 = STR on chr 8
- TCTA repeated between 7 and 20 times
- at least 14 alleles for D8S1179

Question 18

what happens after quantitative fluorescence PCR?

Answer 18

clean up then capillary electrophoresis

Question 19

this can be used to detect aneuploidy

Answer 19

QF-PCR amplification of STR

Question 20

how are QF-PCR products resolved and detected?

Answer 20

capillary electrophoresis