Genetics Lecture

Question 1

What are the main reasons for referral to genetics?

Answer 1

FH in relatives
Diagnosis of genetic conditions
Management of genetic conditions
Genetic counselling

Question 2

What are the main forms of genetic screening?

Answer 2

Antenatal
Neonatal
Child
Adult
Pre-pregnancy
In maturity

Question 3

What are the reproductive choices in genetic conditions?

Answer 3

Nothing/test at birth
CVS
Amniocentesis
Pre-implantation genetic diagnosis
Adoption
Gamete donation
Non-invasive prenatal testing

Question 4

What is the risk of miscarriage in CVS/amnio?

Answer 4

CVS > amnio

0.5 - 1%

Question 5

When is Non-invasive prenatal testing used?

Answer 5

10th week of pregnancy

Fragments of cell-free DNA in maternal blood

Question 6

What is Duchenne Muscular dystrophy?

Answer 6

X-linked

Fatal as early adult

Question 7

How do autosomal dominant conditions present?

Answer 7

Each child 50% chance
No skipped generations
Equal for men and women

Question 8

How is Down’s syndrome screened for?

Answer 8

Maternal age
Triple Screening
CUBS screening
Amniocentesis/fetal DNA

Question 9

Which recessive disorders raise screening issues?

Answer 9

CF (N. europe) W1282X
Sickle cell (African)
Thalassaemia (Mediterranian, Asia)
Tay-Sachs (Ashkenazi Jews)
BRCA1

Question 10

How is CF detected?

Answer 10

Mutation analysis

Question 11

How sensitive is mutation analysis for CF?

Answer 11

80-90%

Question 12

How is Sickle Cell detected?

Answer 12

Haemoglobinpathy MCV
Hb Electrophoresis
Sickledex

Question 13

How is Tay-Sachs detected?

Answer 13

Enzyme activity

Question 14

How common is CF?

Answer 14

1:2500

Question 15

How does CF present in newborns?

Answer 15

Meconium ileus
Lung infections
Pancreatic insufficiency

Question 16

How is CF diagnosed?

Answer 16

Immunoreactive trypsin
Sweat test
Genotyping

Question 17

What is Sickle Cell disease?

Answer 17

Abnormal HB gene

Question 18

How does Sickle Cell disease present?

Answer 18

Pain +++
Cold
Dehydration INfections
Jaundice
Stroke, leg ulcers
Eye problems
Anaesthetic issues

Question 19

What is Tay-Sachs disease?

Answer 19

Progessive genetic Lysosomal storage disease

Hexosaminidase deficiency results in build of of lipids in brain

Question 20

How common is Tay-Sachs?

Answer 20

1 in 25 (Ashkenazi)

1 in 250 (General population)

Question 21

How are newborns screened?

Answer 21

Clinical examination
Hearing
Blood spot

Question 22

Why are babies screened?

Answer 22

Early detection
Early treatment
Reduce anxiety over symptoms

Question 23

What are babies screened for?

Answer 23

PKU
Congenital hypothyroidism
Sickle cell
CF 
MCADD
Homocysteinuria
Isovaleric acidaemia
Maple syrup urine disease

Question 24

How common is Phenylketonuria?

Answer 24

1 in 10,000

Question 25

How is PKU carried?

Answer 25

Recessive condition

Question 26

What is PKU?

Answer 26

Babies unable to break down Phenylalanine

Question 27

How does untreated PKU present?

Answer 27

Irreversible mental disability

Question 28

How is PKU treated?

Answer 28

Diet control by 21 days old

Question 29

How common is Congenital Hypothyroidism?

Answer 29

1 in 4000

Question 30

How does untreated Congenital Hypothyroidism present?

Answer 30

Serious permanent physical and mental disability

Question 31

How is Congenital Hypothyroidism treated?

Answer 31

Levothyroxine by 21 days of age

Question 32

How common is Medium chain Acyl-CoA Dehydrogenase Deficiency MCADD?

Answer 32

1 in 10-20,000

Question 33

How is MCADD passed?

Answer 33

Recessive inherited condition

Question 34

What is MCADD?

Answer 34

Babies cannot break down fat to make energy

Question 35

How does MCADD present?

Answer 35

Serious symptoms in babies that are ill or not feeding

Question 36

When are MCADD typically present?

Answer 36

14 months

Question 37

How is MCADD treated?

Answer 37

Prevent metabolic crisis
Avoid fasting
Monitor meal frequency
IN EMERGENCY:
  - Glucose polymer
  - IV dextrose