Genetics Flashcards
In family tree what is:
1) square
2) circle
3) coloured in?
1) Male
2) Female
3) Disease
What does x linked mean in regards to male transmission?
NOOOO male to male transmission
If a male transmits onto a male it must be what?
Dominant
What are the roles of genetics in repro medicine?
- Pre-conception counselling
- Early pregnancy screening
- Down syndrome screening
- Anomaly scan follow up
- Neonatal screening
What is involved in targeted screening in preconception/early preg?
- Family history – AD / AR/ XL
- Previous obstetric history (loss/miscarriages could be a clue of an underlying genetic abnormality)
- Population carrier screening - AR or XL
What is Gowers sign a classic sign of?
Muscle weakness-treat as emergency in young children-classic sign of Duchennes MD
What does a mutation in haemoglobin gene (HbS) cause?
Sickle cell disease
(Being a carrier of SCD protects from malaria-it is a autosomal recessive condition)
What are some potential complications of sickle cell disease?
- Stroke (overt & silent)
- Cerebrovascular disease (Moyamoya)
- Retinopathy
- Hearing loss/balance problems
- Asthma
- Acute chest syndrome
- Sleep apnoea
- PE
What are the options for early detection & treatment in reproduction?
Pre-implantation genetic diagnosis: PGT-M (available on NHS for 1st child)
Prenatal diagnosis
NIPT- non-invasive prenatal testing
What are some reproductive choices for inherited/known disease?
- Remain childless/adopt
- Gamete donation
How is prenatal diagnosis carried out?
Chorionic villus sampling
Test for what they are concerned about but also check the chromosomes
What is an excellent screening test for trisomies 21, 18 & 13?
Non-invasive prenatal testing/diagnosis- In the plasma is DNA leaked from both mother & foetus-find cell free foetal DNA-look for conditions
What are some advantages of non invasive prenatal testing/diagnosis?
- Low false positive rate gives potential to avoid an invasive test which carries a risk of miscarriage
- Clarity of reported results - low chance or high chance of aneuploidy
What are the limitations of non invasive prenatal testing/diagnosis?
- May be false negative or no result with a low fetal fraction
- May be a false positive with ‘vanishing’ twin, maternal cancer or placental mosaicism
What are the ways that abnormal scans are investigated?
- Chromosomal microarray
- Gene panel e.g. skeletal dysplasia (Quick, targeted interpretation)
- Prenatal exome sequencing (Interpretation has to be phenotypically driven, Slower, more expensive)
