Genetics Flashcards

0
Q

What does genetic risk increase with

A

Number of affected fam members

Frequency in population

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1
Q

Big 5 genetic defects

A
Congenital heart disease
NTDs
Hemoglobin disorders
Down's syndrome
G6PD deficiency
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2
Q

Types of genes affected in NTDs

A
Folate metabolism ( not SA) 
Other metabolic genes
Genes related to neural tube development (planar cell polarization pathway)
Neural plate bending (SHH) 
Epigenetic
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3
Q

‘Syndromic’ NTD conditions

A

Downs
Triploidy

Meckel gruber (AR)
Curriano syndrome (AD)
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4
Q

Environmental factors in NTDs

A
Seasonal variation
Geographic variation 
Nutritional 
Twins
Teratogens (alcohol, anticonvulsant, hyperthermia)
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5
Q

Prenatal diagnosis of NTD

A
U/S
AFP
Maternal serum screen
Second trimester aneuploidy screening
Amnio = very rare
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6
Q

Congenital defect in platelet function

A

Von Willebrand disease (AD)

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7
Q

X linked recessive bleeding disorder

A

Haemophillia A or B

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8
Q

Why may females bleed in haemophilia

A

One X eg Turners syndrome
Both copies of gene
Skewered X inactivation pattern
Other X abnormalities

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9
Q

Congenital thrombosing disorders

A

Antithrombin 3 deficiency
Protein C and S def
Factor V Leiden
Prothrombin mutation

All autosomal dominant but reduced penetrance

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10
Q

Aetiology of NTDs

A

Isolated (familiality + environmental factors)

Spectrum of disorders (commonly meningomyelocoele and anencephaly)

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11
Q

Teratogens in NTD

A

Maternal IDDM
Anticonvulsants (valproate/ carbamazepine)
Alcohol
Hyperthermia

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12
Q

Outcome in prenatal diagnosis of NTD depends on..

A

Type and level of lesion
Associated findings
Post natal course (hydrocephalus / shunt complications)

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13
Q

Primary prevention of NTDs

A
Improve health, nutrition
Family planning
Rx chronic diseases eg DM, epilepsy
Avoid teratogens
Genetic counseling 
PRECONSEPTUAL FOLATE
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14
Q

Folic acid doses

A

1 month before preg to 3 months after birth

400ug ‘‘normal risk’’
4mg previous NTD, affected parent, 2nd degree relative

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15
Q

Secondary prevention of NTDs

A
Identify woman at risk
U/S
Genetic counseling 
Voluntary antenatal testing (if appropriate)
Access to voluntary TOP
16
Q

Tertiary prevention of NTDs

A
Early/ accurate diagnosis
Intervention to avoid/ minimize complications
Medical/ surgical Rx
Rehab therapy
Psychosocial support
17
Q

Congenital bleeding disorders

A

Rare AR deficiencies (eg factor Xl def - Ashkenazi Jews)(prothrombin/fibrinogen defs)
X linked recessive - Haemophilia
Congenital platelet defects - Von Willebrand Disease

18
Q

Clinical presentation of haemophilia

A

Spontaneous bleeds into joints/muscles

Excessive bleeding after trauma or surgery

19
Q

Management of haemophilia

A

Factor replacement (acute vs prophylactic)
Monitor for inhibitors
Supportive therapy eg physio
Genetic counseling

20
Q

Problems with gene based therapy

A
Getting to target
Site of insertion
Effects of vector NB immune
Expression (how much, when, how long, control)
Timing of replacement
21
Q

Why is gene therapy for haemophilia possibly possible

A
Small gene
Single target organ (liver)
Only small amount of clotting factor needed
Continuous production of factor
No effects on development
22
Q

Haemophilia A is a def in..

A

Factor Vlll

23
Q

Haemophilia B is a def in

A

Factor lX

24
Q

Clinical presentation of thrombosing disorders

A

Venous thrombosis/ embolism

Pregnancy loss

25
Q

When is a genetic disorder more likely in thrombosis

A
Young
No precipitant
Unusual site
Recurrent
Family history
26
Q

Management of thrombosis

A

Anticoagulation
Avoid risk factors eg COC
Genetic counseling

27
Q

What is Factor V Leiden

A

Substitution of amino acid (from A/G sub)

Abnormal factor V. Resistance to activated protein C. Less control over thrombin production.

28
Q

Who do we test for low penetrance common mutations causing thrombosis

A
First unprovoked VTE
Recurrent VTE
Thrombosis in unusual sites (cerebral, mesenteric, portal, hepatic)
VTE in pregnancy
VTE associated with COC and HRT
FDR with VTE under 50yrs
29
Q

Things to take into consideration in genetic counseling

A
  • age
  • parity
  • social/cultural background
  • religion
  • support
  • finances
  • previous experience with disability
30
Q

Genetic disorders that increase risk of intracranial haemorrhage

A
  • haemophilia A (x linked recessive)
  • haemophilia B (x linked recessive)
  • Von willebrands disease (AR)
31
Q

4 aspects of secondary prevention of ntds

A
  • maternal AFP
  • 2nd trimester fetal anomaly ultrasound
  • genetic counseling
  • access to voluntary top
32
Q

Factors that influence recurrence risk of ntds

A
  • population incidence
  • family history of ntds
  • syndromic features
  • teratogen exposure
  • maternal diabetes
  • use of preconceptual folate