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Obstetrics and Gynaecology > Genetics > Flashcards

Genetics Flashcards

1
Q

What questions to ask if Haemophilia B

A

-is the mom symptomatic

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2
Q

What happens to Factor 8 and Factor 9 in pregnancy?

A

It increases - increases coagulopathy

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3
Q

In which week is the test for Down Syndrome done?

A

11th week

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4
Q

How do you screen the baby for Down’s syndrome?

A

Nuchal translucency: Look at the gap btw the neck and the back wall. if the lymphatic development is slow, the gap is too big. ig bigger than 3.6 (it could indicate a change in lymphatic development)

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5
Q

When can amniocentesis be done?

A

15 weeks

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6
Q

Non-invasive pre-natal testing

A

Placenta sheds foetal DNA to the maternal circulation - 10% of the serum in the mom’s blood comes from the baby

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7
Q

Confined placental mosiacism

A

cells that go to make the placenta have an abnormal chromosome make up- because of multiple divisions. Hence CVS can look at mosaics without it the baby actually having it

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8
Q

What are the cons of non-invasice pre-natal testing?

A

Can have false positives - because of mosaic divisions in placental cells that keep dividing –> can have trisomy 21;

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9
Q

What are the steps in Down’s syndrome screening?

A

1st - Combined test: US and blood markers in mother (screening)
2nd - High risk –> NIPT lots and lots of counts of each chromosome - marginal over-representation of trisomy 21
+/- Diagnostic –> need to follow it with amniocentesis or no invasive test

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10
Q

What other tests can be done with non-invasice pre-natal screening?

A

trisomy 18

trisomy 13

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11
Q

Heal break test

A

Metabolic conditions

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12
Q

Is there much of a difference when screening for Down’s wrt end point in care?

A

not much of a difference, but atleast it prepares the mother for the scenario

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13
Q

When can you opt for a ToP?

A

surgical treatment - before 13 weeks
Induction - thereafter

no time limit on TOP if there is a risk of serious abnormality in the child or to the health of the mother

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14
Q

Would you sign a TOP for anencephaly?

A

Anencephaly - no brain development

Can sign it

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15
Q

When can CVS be done?

A

11 - 14 weeks

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16
Q

Features of Edwards syndrome

A
  • every cell has a trisomy 18
  • Will die before or shortly after birth
  • not inherited
17
Q

Features of mosaic 18

A
  • not all cells have a trisomy 18
  • 7/10 babies born with mosaic trisomy will live for at least a year and, in rare cases, may survive into early adulthood
  • Severity depends on the number of and type of cells that have the extra chromosome. Some babies may only be mildly affected, while some can be severely disabled.
18
Q

Would you give a TOP for a patient with hand abnormality?

A

It can be a part of another syndrome, hence it can be variable:

falcon anaemia
DiGeorge’s syndrome
Thrombocytopaenia

19
Q

Would you follow up with a baby girl with Haemophilia?

A

No, write it up to haematology and have a chat when she reaches a child bearing age

20
Q

What is done in invasive testing?

A

1st line - Chromosome testing- chromosome microarray

But can’t pick up balanced chromosome abnormalities - just deletions or additions

21
Q

Pros of Chromosome microarray

A

high resolution
technologically easier
rapid

22
Q

Cons of chromosome microarray

A
  • won’t detect balanced chromosomal abnormalities
  • also finds polymorphisms - don’t need to report as you don’t know
  • may make incidental findings - might have to report it as it might be important for the baby and the mom might have it as well
23
Q

When do you do a aCGH?

A
  • chromosome trisomy
  • foetal abnormality on scanning
  • parent has a balanced chromosomal rearrangement
24
Q

With PCR which part of the genome do you sequence?

A

the part that you are interested in

25
Q

What is a floppy baby?

A
  • rag doll
  • lack of head control
  • increased range of movement
  • frog legged
  • feel like they’ll fall out of your grasp
  • possibly breathing difficulties
  • low tone
26
Q

Causes of low tone:

A

centrally - cortex, spinal cord, anterior horn cells/ motor neurons

Peripheral - neuromuscular junction

27
Q

DIfferential diagnosis of low tone:

A

Central:

  • hypoxic ischaemic encephalopathy
  • intracranial haemorrhage
  • chromosomal abnormality
  • congenital infections (TORCH - Toxoplasmosis, Rubella, CMV, Herpes, HIV, Hep)
  • acquired infection
  • peroxismal disorders
  • drug side effects (eg: benzodiazepines)

Spinal cord:

  • birth trauma (expecially breech delivery)
  • syringomyelia

Anterior Horn Cell:
-spinal muscle dystrophy

28
Q

Do you do a rubella test now?

A

No, before AB for Rubella used to be checked

29
Q

What examination would you do on a floppy baby?

A

central: - normal strength, normal/ increased DTRs, +/- seizures, +/ dysmoprhic features, reduced alertness

Anterior horn cell: generalised weakness, decreased/ absent DTRs, fasciculations, often described as alert

NM Junction
-weakness, face/eyes/bulbnar
-normal DTRs
-no fasiculations
\+/- arthrogryposis contractures

Muscle

  • weakness, proximal >distal, face, EOM
  • decreased DTRs

Nerve
-weakness distal>proximal
-decreased/ absent DTRs
+/- fasiculations

30
Q

What steps will be done next after floppy baby?

A

Bloods - genetics, metabolic, congenital infection screening, CK (duchennes)

Neurology review (EEG/ EMG after 6 months)

Imaging:
cranial USS
MRI

31
Q

If no family history or no result on microarray, does it mean that there is no abnormality?

A

No, can have a de novo mutation as well!

can do a NGS (next generation sequencing)

32
Q

How many cranial nerves can you test on a neonate?

A

Everything except smell

33
Q

Anterior horn cell dysfunction causes which disease?

A

spinomuscular atrophy

34
Q

Prader-Willi syndrome

A

hypotonic

35
Q

Which test would you do most rapidly?

A
  • Myotonic dystrophy
  • spinal muscular atrophy
  • prader-willi syndrome
36
Q

Spinal muscular atrophy Type 1

A

very expensive management

severe disease

Obstetrics and Gynaecology (2 decks)

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