Genetics in obstetric care

Question 1

Reasons for referral to genetics

Answer 1

FH
diagnosis of genetic conditions
genetic counselling
management

Question 2

7 things people need to know before undergoing a genetic test

Answer 2

what it is for 
likely to be +ve?
what if it is +ve?
What if it is -ve?
false positives and negatives 
implications on family members
DNA stored

Question 3

the 2 types of pregnancy screening/testing are

Answer 3

targeted

whole population

Question 4

Reproductive choices for testing

Answer 4

CVS 
amniocentesis 
pre implantation genetics
nothing/test at birth
adoption 
gamete donation 
non invasive prenatal diagnosis

Question 5

x linked recessive trait with carrier mother and example

Answer 5

1 affected son, 1 carrier daughter and 2 unaffected

duchennes

Question 6

autosomal dominant trait with 1 parent affected

Answer 6

50% chance

no skipped generations

Question 7

Autosomal recessive with both parent carriers and example

Answer 7

1 normal, 2 carriers and 1 affected

sickle cell

Question 8

screening for down’s syndrome

Answer 8

maternal age 
free fetal DNA
triple screening - AFP, hCG and uE3
CUBS 
amniocentesis

Question 9

list some common recessive disorders

Answer 9

CF, sickle cell, Tay Sachs, thalassaemia, BRCA1

Question 10

Diagnosis of CF

Answer 10

immunoreactive trypsin - 6 weeks

sweat test and genotype

Question 11

Sickling symptoms

Answer 11

pain - cold - dehydration - leg ulcers - eyes - kidneys - jaundice - infections - anaesthetic issues - stroke

Question 12

Tay sachs - what is it?

Answer 12

progressive genetic lysosomal storage disease

hex A deficiency - build up of lipids in nerve cells in brain

Question 13

Prognosis for Tay sachs

Answer 13

progressive from 6 months - fatal at 3-5 years

Question 14

carriers in Ashkenazi jews and general population

Answer 14

jews - 1 in 25

general - 1 in 250

Question 15

3 parts of newborn screening

Answer 15

clinical exam
hearing
blood spot - 3 to 5 days

Question 16

3 reasons why we screen babies

Answer 16

1. early detection of pre-symptomatic
2. early treatment
3. reduce anxiety over symptoms

Question 17

What do we screen babies for?

Answer 17

PKU, CHT, CF, sickle cell

MCADD, homocysteinuria, maple syrup urine disease

Question 18

PKU inheritance

Answer 18

recessive

Question 19

PKU - what is it?

Answer 19

unable to break down the amino acid phenylalanine

Question 20

What happens to baby in PKU?

Answer 20

serious irreversible mental disability if not treated

Question 21

Treatment of PKU

Answer 21

start within 21 days - diet

Question 22

How much of CHT is inherited?

Answer 22

1 in 10 cases

Question 23

Treating CHT

Answer 23

thyroxine tablets by day 21

Question 24

inheritance of MCADD

Answer 24

recessive

Question 25

MCADD

Answer 25

cannot easily breakdown fat so if skip meals can be life threatening

Question 26

age of presentation and mortality in MCADD

Answer 26

14 months - 25%

Question 27

Treating MCADD

Answer 27

avoid fasting and have frequent meals

emergency - glucose polymer and IV dextrose

Question 28

Pros and cons of next generation sequencing

Answer 28

costs fall and quicker to interpret data

still need scientists, variant interpretation takes time and still need to confirm result