Antenatal and Postnatal Screening

Question 1

What is the function of antenatal screening?

Answer 1

To identify the risk of a disorder so that further tests and a prenatal diagnosis can be offered.

Question 2

How many ultrasound scans are pregnant women given?

Answer 2

Two.

Question 3

What do dating scans do?

Answer 3

Determine pregnancy stage and due date.

Question 4

When do dating scans take place?

Answer 4

Between 8 and 14 weeks.

Question 5

What may anomaly scan detect?

Answer 5

Serious physical abnormalities in the fetus.

Question 6

When do anomaly scans take place?

Answer 6

Between 18 and 20 weeks.

Question 7

Why are blood and urine test carried out during pregnancy?

Answer 7

To monitor the concentrations of marker chemicals.

Question 8

What are examples of diagnostic testing?

Answer 8

Amniocentesis and Chorionic Villus Sampling (CVS).

Question 9

Which diagnostic test has a higher chance of miscarriage?

Answer 9

Chorionic Villus Sampling (CVS).

Question 10

Why is a karyotype produced from the cultured cells?

Answer 10

To diagnose a range of conditions.

Question 11

What does a karyotype show?

Answer 11

An individual’s chromosomes arranged as homologous pairs.

Question 12

What are the four patterns of inheritance?

Answer 12

• Autosomal recessive
• Autosomal dominant
• Incomplete dominance
• Sex linked recessive single gene disorders

Question 13

How often is autosomal recessive inheritance expressed?

Answer 13

Relatively rarely

Question 14

Are males and females affected differently by autosomal recessive?

Answer 14

No

Question 15

What is the genotype of all autosomal recessive sufferers?

Answer 15

Homozygous recessive.

Question 16

How are males and females affected by autosomal dominant inheritance?

Answer 16

They are affected equally.

Question 17

What is the genotype of autosomal dominant non-sufferers?

Answer 17

Homozygous recessive.

Question 18

What is the genotype of sufferers of autosomal dominant inheritance?

Answer 18

Homozygous dominant or heterozygous.

Question 19

What is incomplete dominance?

Answer 19

When the dominant allele does not fully express itself.

Question 20

Which sex chromosome carries more genes?

Answer 20

X.

Question 21

What are genes which are carried on the same sex chromosome called?

Answer 21

Sex - linked.

Question 22

What is the genotype of sufferers of sex linked traits?

Answer 22

Homozygous recessive.

Question 23

What is the genotype of male non-sufferers?

Answer 23

Homozygous dominant.

Question 24

How are heterozygous female carriers affected?

Answer 24

They don’t suffer from the condition but carry a copy of the gene which they can pass on to their offspring.

Question 25

Are males and females affected differently?

Answer 25

Males are affected much more frequently.

Question 26

Will any sons of an affected male show the trait?

Answer 26

No

Question 27

Will any grandsons of the affected male show the trait?

Answer 27

Some may.

Question 28

What is the purpose of Chronic Villus Sampling?

Answer 28

To diagnose a range of conditions like Down Syndrome.

Question 29

What is the purpose of post-natal diagnostic testing?

Answer 29

To detect metabolic disorders like phenylketonuria.

Question 30

Where are the cells used for CVS taken from?

Answer 30

The placenta.

Question 31

Where are the cells used in amniocentesis taken from?

Answer 31

The amniotic fluid.