Genetic

Question 1

What are the two different procedures to genetically analyse an embyro

Answer 1

Chorionic Villus Sampling and Amniocentisis

Question 2

What is the preferred time frame of CVS and risk

Answer 2

10-15 weeks and 1% increased risk on background

Question 3

What is the preferred time frame for amniocentisis and risk

Answer 3

15-17 weeks and 0.5% increased risk on background

Question 4

What is nuchal translucency

Answer 4

Is a specific ultrasound diagnostic factor that looks at the amount of fluid in the nuchal ligament region of a embyro. Greater than 3mm indicates an increased risk for a range of diseases

Question 5

What are the markers in maternal blood to determine risk in the first trimester

Answer 5

hCG and PAPP-A

Question 6

What are the risks of Trisomy 21

Answer 6

1 in 660

Question 7

What is edward’s syndrome

Answer 7

Trisomy 18, - Many miscarriage

• Overlapping fingers
• Heart defects
• Development disability

Question 8

What is a Barr Body

Answer 8

An inactivated X chromosome in female cells, however not all genes are suppressed as Turner Syndrome patients are infertile

Question 9

What is heterochromatin

Answer 9

Condensed chromatin that is peripheral and will not be transcribed due to extensive histone binding

Question 10

What is euchromatin

Answer 10

Is DNA that is not wrapped around histones, is central and readily transcribed

Question 11

What are the typical methylation and Acetylation patterns in heterochromatin

Answer 11

high methylation and low acetylation

Question 12

What are the typical methylation and Acetylation patterns in euchromatin

Answer 12

Low methylation and high acetylation

Question 13

What is maternal and paternal genomic imprinting

Answer 13

Will only transcribe/activate genes that are from specific parents, will then reset to your gender during meiosis

Question 14

What are some genomic imprinting diseases

Answer 14

Prader-Willi Syndrome (paternal) and Angleman and Beckwith-Wiedemann Syndrome(Maternal)

Question 15

What is the mechanism of inheritance of paternal imprinting disorders

Answer 15

Affected mothers can only have carrier children

Affected fathers can only have affected children

Question 16

What is the mechanism of inheritance of maternal imprinting disorders

Answer 16

Affected fathers can only have carrier children

Affected mothers can only have affected children

Question 17

What is Angelman syndrome

Answer 17

• Intellectual disability
  
  • Absent speech
  • Innaproppriate laughter
    Maternal imprinting problem

Question 18

What is Prader-Willi Syndrome

Answer 18

Overgrowth problems

Paternal imprinting problem

Question 19

What is Beckwith-Wiedemann syndrome

Answer 19

Materanl imprinting problems where neonates are born with large tongues, anterior abdominal wall defects and neonatal hypoglycaemia

Question 20

What is Uniparental disomy

Answer 20

Where the child has only the chromosonal imformation from one parent, ie sperm fertilises an egg with no DNA. Will be rescued by mitotic escape. Or can occur from when am egg has two copies due to an error in miosis I

Question 21

What are the markers to examine in mothers blood in second trimester

Answer 21

hCG and inhibinA, a-feto protein and Oestriol. The first two markers will be up in Trisomy 21 with the other two being down

Question 22

What other factors are taken into account when calculating risk from first trimester combined screening

Answer 22

Age, weight, family history and age of gestation combined with ultrasound and nuchal translucency