Genetics and CVS disease Flashcards
What is meant by Copy number variation?
Cause of congenital defects (incl. Congenital heart disease)
Can be whole chromosome - monosomy, trisomy
Can be part of a chromosome - 22q11 deletion, Williams
What is meant by single nucleotide variation?
Mutation in which single nucleotide is fucked up
Mendelian disorders:
- Noonan/CFC
- Marfan
- SVAS
- Holt-Oram
What causes Down’s syndrome?
Trisomy 21
95% maternal non-disjunction (mat age)
3% translocation
2% mosaic
How is Down’s syndrome relevant to the Cardiovascular system?
15% born with Atrial septal defect
How does Down’s syndrome affect the digestive system’s development?
8% born with Duodenum atresia
How would an ultrasound scan indicate that a foetus may have Down’s syndrome?
Nuchal translucency
This is a translucent area on the back of the neck at 12 weeks - thickness of area measured
Nuchal prenatal screening scan is done to detect abnormalities of the CVS & can indicate risk of Down’s S etc
What is the name given to blocked lymphatic fluid that is trapped, commonly in the head/neck area of a developing foetus?
Cystic hygroma
Associated with congenital HD
What percentage of foetuses with congenital heart diseases have abnormal chromosomes?
19%
What percentage of new borns with congenital heart diseases have chromosomal abnormalities?
13%
What chromosomal abnormality causes Turner’s syndrome?
45, X
30% mosaic
5% 45,X/46XY
What are the signs/effects of Turner syndrome?
Neck webbing
Short stature
Puffy hands
Coarctation of aorta
Gonadal dysgenesis
Is neck webbing only associated with Turner syndrome?
No, the syndromes with webbed necks are:
Turner Noonan CFC Leopard Costello
How would you identify Noonan syndrome?
Neck webbing
Short stature
Cryptorchidism (testis don’t drop from abdomen)
Characteristic face
Pulmonary stenosis
How would you identify Cardio-Facio-Cutaneous syndrome? (CFC)
Ectodermal problems
Developmental delay
Noonan like:
- Neck webbing
- Short stature
- Cryptorchidism
- Characteristic face
- Pulmonary stenosis
How would you identify Leopard syndrome?
Noonan like
Also:
- Multiple lentigenes (brown patches on skin)
- Deafness
How would you identify Costello syndrome?
Noonan like but with:
- Thickened skin folds
- Warts
- Cardiomyopathy
- Later cancer risk
Leopard, Costello, CFC & Noonan syndromes are all associated with defects in enzymes in what cellular pathway?
MAPK pathway
Mitogen activated protein kinase
How would you identify 22q11 deletion syndrome?
CATCH22
Cardiac malformation Abnormal facies (distinct facial look/expression) Thymic hypoplasia Cleft palate Hypoparathyroidism
22q11 deletion
What functional abnormalities are experienced by people with 22q11 DS?
(assuming any defects at birth are fixed)
Renal
Psychiatric
What 2 syndromes make up 22q11 DS?
DiGeorge syndrome
Shprintzen syndrome
What factors of 22q11 DS does DIGeorge syndrome account for?
Thymic hypoplasia
Hypoparathyroidism
Outflow tract myocardial malformation
What factors of 22q11 ds does Shprintzen syndrome account for?
Cleft palate / malformation of palate
Outflow tract myocardial malformation
Facies (face)
Autosomal dominance
How would you identify William’s syndrome?
Aortic stenosis - supravalvular Hypercalcaemia 5th finger clinodactyly - bent pinky Facies Cocktail party manner
What causes Williams syndrome?
Deletion of several continuous genes on the long arm of chromosome 7 including elastin and LIM kinase
What is the risk and effects of consuming alcohol when pregnant?
Foetal alcohol syndrome - 3-5 units per week
Effects: IUGR < 10th centile Head < 10th centile ADHD Face
(IUGR = intrauterine growth restriction)
One of the JAMTHREADS drugs for treatment is teratogenic
Which one is it?
Epilepsy
Antiepileptics are teratogenic
Contraction of what can cause german measles?
Rubella
What JAMTHREADS illness is teratogenic in itself?
Diabetes
Which parent is more generally likely to pass on a simple congenital heart disease?
Mother
VSD is associated with deficiency of what necessary vitamin thing?
Folate
What are the cardiovascular connective tissue diseases?
Marfan
Loeys-Dietz
Ehlers Danlos
FTAA
What are the different Familial arrhrythmias?
Long QT
Brugada
CPVT
ARVC
What are the different familial cardiomyopathy diseases?
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
ARVC
Mutation of what gene causes Marfan’s syndrome?
Fibrillin 1 gene
Chromosome 15q21
What system is used to diagnose Marfan’s syndrome?
GHENT criteria 2010
Must have 2 positive findings
Describe the GHENT criteria
Aortic dilation/dissection
Ectopia lentis
Fibrillin 1 mutation
1 unequivocally affected relative
Systemic score - must have 7 or more of:
- Skeletal
- Skin
- Respiratory
- Dural ectasia (dilation of dural sac around spinal cord)
- Mitral valve prolapse
- Myopia (short sightedness)
Why is ECHO useful for diagnosing Marfan’s
ECHO is mandatory
Measure diameter of aortic root at sinus of Valsalva, showing extent of dilation
Identify mitral valve prolapse
Why could a blood test be useful for diagnosing Marfan’s?
Genome sequencing (or other) can identify Fibrillin 1 gene mutations
This is identifiable in 70-90% of people with Marfan’s
Why is an X ray a useful imaging technique for diagnosing Marfan’s syndrome?
Pelvic Xray will identify Protrusio acetabulae (skeletal feature)
CXR (or CT) can identify Apical blebs (Respiratory feature)
Why are MRI’s useful for diagnosing Marfan’s?
Lumbar MRI will identify Dural ectasia
Cardiac MRI will identify aortic dilation/dissection
Even if a father and son both have Marfan’s syndrome, they might show different symptoms & signs
Why is this?
Different symptoms present at different times
Summarise the treatment for Marfan’s syndrome
Prophylactic:
Antihypertensives - Beta blockers, ARBs, ANG2 type 2 receptor blockers, calcium channel blockers
Aortic root surgery - if sinus of Valsalva > 5.5cm or 5% growth per year
Advice to avoid contact sports and heavy exertion
Annual review - ECHO
What findings on an ultrasound scan of a foetus would indicate an increased risk of congenital heart disease?
Nuchal translucency thickness
Cystic hygroma
Mutations involving what gene & chromosome give rise to Noonan syndrome and Noonan-like syndromes?
PTPN11
On chromosome 12
What type of trait is Noonan syndrome?
Autosomal dominant
pretty much all of the syndromes in this lecture are autosomal dominant
What is CPVT?
Catecholaminergic polymorphic ventricular tachycardia
It is one of the familial arrhythmias
What is ARVC?
Arrhythmogenic right ventricular cardiomyopathy
One of the familial arrhythmias (although it has a cardiomyopathy aspect as well)
What would be a typical signs on presentation of someone that has Marfan’s?
Tall with long arms
Hypermobile/flexible
Stretch marks on lower back
Pectus carinatum
History of myopia, lung problems
Family history of Cardio disease and tallness and all that shite
What are the main features of Loeys-Dietz syndrome?
Marfan’s like signs
Arterial weakening / dissection
Tortuosity
Bifid uvula / cleft palate
Hypertelorism - increased distance between the eyes
skin and skeletal findings
What mutation causes loeys-dietz?
Chromosome 3p22 or 9q33
What chromosomal mutations are associated with Familial thoracic aortic aneurysms?
11q 5q 3p22 16p13 10q22-24
Bicuspid aortic valve
FTAA
What features characterise the MASS phenotype?
myopia mitral valve prolapse mild aortic dilatation (<2sd) striae minor skeletal involvement May be fibrillinopathy
What arrhythmia is associated with ion chanellopathy and why is it relevant to Sudden Unexpected Death?
Autopsy of people with SUD showed that 35% had ion channelopathy
The majority of these is Long QT syndrome
Some study that was done studied the relatives of people who had Sudden unexpected death
What did this investigation show?
40-53% of SUD patient’s 1st degree relatives had an identifiable inherited heart disease
basically indicates that inherited heart diseases put patient at risk of Sudden unexpected death
What is Romano-ward syndrome?
Form of Long QT syndrome
Key feature is that only the conduction properties of the heart are affected whereas other long QT syndromes have effects elsewhere in the body
What are the risks posed to someone with Romano-Ward syndrome?
Syncope
Seizures
Sudden Death
What features of an ECG would indicate Romano-Ward syndrome?
Long QT interval
Repolarisation anomalies (T/U waves)
Paroxysmal polymorphic VT (Torsades de Pointes)
What is Jervell Lange-Neilsen syndrome?
Almost identical to Romano-Ward syndrome
Form of Long QT syndrome with risks of Syncope, seizures and sudden death
+ sensorineural deafness !
What are the main features of Brugada syndrome?
Sudden cardiac death or VT/VF and Type 1 Brugada ECG
prolonged PR interval
enlarged LV / poor LV function
What group of people is Brugada syndrome most common in?
Young men, especially of far eastern origin
What is the test done to diagnose Brugada syndrome?
Ajmaline challenge
What mutation most commonly causes Brugada syndrome?
SCN5A
What is the management route for Brugada syndrome?
Avoid Fever Avoid excess alcohol Avoid overeating (- Vagal effects)
ICD
What is AVC?
Atrioventricular canal defect
ASD + VSD + Improperly formed Mitral and/or Tricuspid valves
How is Atrioventricular canal investigated?
ECHO / CMRI (RV dyskinesia)
ECG - epsilon waves , T wave inversion
SAECG - late potentials
Family history / investigation of pathogenic gene variant
What histological abnormality is present in Atrioventricular canal patients?
Fatty infiltration of Right Ventricle
What is the prevalence of Hypertrophic cardiomyopathy?
1/500
What HCM patients are most at risk of sudden cardiac death?
SCD most common in those diagnoses <14 years old
Or in those who are symptomatic
What are the modifiers for the prognosis of a patients with HCM?
Lifestyle - sport etc
Other genes - eg ACE polymorphism
Which allelic form of HCM is most common?
Monoallelic
Most common is Myosin binding protein gene mutation (MYBPC3)
What histological feature is present in H(O)CM?
Myofibrillar disarray
What are the steps in investigating / diagnosing Dilated cardiomyopathy?
ECHO
Exclude other conditions
Family history - look for history of SCD or cardiomyopathy evidence
Genetic testing
What genetic testing for what genes may be done to investigate Dilated cardiomyopathy?
Titin LMNA SCN5A Dystrophin Sarcomere genes
What is the difference between whole genome sequencing and whole exome sequencing?
Exome sequencing only involves the parts of genes that code for proteins