Ante and postnatal screening

Question 1

What does antenatal and postnatal screening involve?

Answer 1

Testing for diseases or conditions in a fetus or embryo before it is born

Question 2

What does antenatal screening identify?

Answer 2

The risk of a disorder so that further tests and a prenatal diagnosis can be offered

Question 3

What do common antenatal testing procedures include?

Answer 3

ultrasound scanning, amniocentesis, chorionic villus sampling (CVS) and rhesus antibody testing

Question 4

What are three uses of an ultrasound used to produce?

Answer 4

An ultrasound image on a computer screen ,gestational dating scan and anomaly scan

Question 5

What is a gestational dating scan mean?

Answer 5

which is used to determine the stage of pregnancy and date that the baby is due

Question 6

What is an anomaly scan?

Answer 6

Used to detect the presence of serious physical problems in the fetus

Question 7

What is an ultrasound?

Answer 7

image on a computer screen

Question 8

Why are biochemical tests carried out?

Answer 8

To detect marker chemicals that are produced during normal physiological changes that take place during pregnancy

Question 9

What is a screening procedure?

Answer 9

Tests such as ultrasound imaging that indicates the possible presence of a disorder

Question 10

What can diagnostic tests like amniocentesis and CVS confirm?

Answer 10

The presence of conditions such as down syndrome

Question 11

What can cells from amniocentesis and CVS do?

Answer 11

Be cultured to obtain sufficient cells to produce karyotype

Question 12

What is karyotype?

Answer 12

An image of an individual’s chromosomes arranged in homologous pairs

Question 13

Why is a karyotype used?

Answer 13

To identify anomalies in the number or structure of chromosomes

Question 14

What are problems with diagnostic test like amniocentesis and CVS?

Answer 14

THey are invasive and carry a small risk of inducing miscarriage

Question 15

When can CVS be carried out?

Answer 15

Before amniocentesis but has a higher risk of inducing miscarriage

Question 16

Why is Rhesus antibody carried out earlier in a pregnancy?

Answer 16

To determine the rhesus status of the mother, to ensure that she shows no immune responses to her fetus

Question 17

what complications can event of a second pregnancy

Answer 17

If a mother is rhesus negative and the fetus is rhesus positive

Question 18

What is given to negative rhesus mothers after sensitising events such as the birth of a baby?

Answer 18

Anti rhesus antibodies

Question 19

What does postnatal screening involve?

Answer 19

Health checks that are carried out after the birth of the baby. These are aimed at detecting certain conditions or abnormalities

Question 20

What is postnatal testing used to detect?

Answer 20

Metabolic disorders such as phenylketonuria (PKU)

Question 21

What is PKU?

Answer 21

An inborn error of metabolism

Question 22

How is PKU caused?

Answer 22

By an autosomal recessive genetic disorder

Question 23

What can individuals with PKU cannot do?

Answer 23

Metabolise excess phenylalanine

Question 24

What can happen if PKU is not detected soon after birth?

Answer 24

The baby’s mental development can be affected

Question 25

What do people with PKU have to do?

Answer 25

Be placed on a restricted diet that lacks the amino acid phenylalanine

Question 26

What are pedigree charts compiled and used to analyse?

Answer 26

Patterns of inheritance in genetic screening and counselling

Question 27

What are pedigree charts constructed to do?

Answer 27

Provide information and advice in situations where there is the possibility of passing on a genetic disorder to potential offspring

Question 28

What are pedigree charts compiled to do?

Answer 28

To analyse patterns of inheritance in genetic screening and counselling

Question 29

In what situation are pedigree charts used to provide information and advice?

Answer 29

Where there is a possibility of passing on a genetic disorder to potential offspring

Question 30

What can pedigree charts be used to analyse?

Answer 30

Patterns of inheritance involving autosomal recessive, autosomal dominant, incomplete dominance and sex linked recessive single gene disorders

Question 31

What are alleles?

Answer 31

Forms of the same genes

Question 32

What are homozygous alleles?

Answer 32

Individuals have two copies of the same allele

Question 33

What are heterozygous alleles?

Answer 33

Individuales have copies of two different alleles

Question 34

Describe cystic fibrosis an autosomal recessive disorder

Answer 34

Is expressed relatively rarely in the offspring | It affects males and females equally and may skip generations

Question 35

When does an autosomal disorder such as Huntington's disease show up?

Answer 35

Every generation and affects males and females equally

Question 36

What does autosomal incomplete dominance mean?

Answer 36

The fully expressed form of the condition is rare, the partly expressed form is more common. Males and females are affected equally

Question 37

Who is more affected in sex-linked recessive disorders?

Answer 37

Males are affected more than females. Male offspring receive the condition from their mother; fathers cannot pass the condition on to their sons and female offspring can only be affected if the father has the condition and the mother is at least a carrier

Question 38

What three things involve the production of a karyotype

Answer 38

Anomaly scan, amniocentesis and chorionic villus sampling

Question 39

When does a dating scan takes place?

Answer 39

Between 8 and 14 days

Question 40

Why are blood and urine tests carried throughout the pregnancy

Answer 40

To monitor the concentration of marker chemicals

Question 41

Why to cells from samples are used to be cultured to obtain sufficient cells

Answer 41

to produce a karyotype to diagnose a range of conditions

Question 42

What decision has to be made when deciding to proceed with theses tests?

Answer 42

The element of risk will be assessed will the decisions the individuals concerned are likely to make if a test is positive

Question 43

What are the patterns of inheritance

Answer 43

autosomal recessive autosomal dominant incomplete dominance sex-linked recessive single gene disorder

Question 44

What is the diagnostic testing for phenylketonuria

Answer 44

In PKU a substitution mutation means that the enzyme which converts phenylalanine to tyrosine is non-functional