Paeds: Genetics Flashcards

1
Q

what is Down’s Syndrome caused by?

A

trisomy 21

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2
Q

what are the dysmorphic features of Down’s syndrome? (8)

A
  • hypotonia
  • Brachycephaly (small head with a flat back)
  • short neck
  • short stature
  • flattened face + nose
  • prominent epicanthic folds
  • upwards sloping palpable fissures
  • single palmar crease
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3
Q

complications of Down’s syndrome (9)

A
  1. learning disability
  2. recurrent otitis media
  3. deafness: eustachian tube abnormalities –> glue ear + conductive hearing loss
  4. visual problems: myopia, strabismus + cataracts
  5. hypothyroidism
  6. cardiac defects: ASD, VSD, PDA, ToF
  7. atlantoaxial instability
  8. leukaemia more common
  9. dementia more common
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4
Q

3 antenatal screening tests for Down’s screening

A
  1. 1st line: Combined test
  2. Triple test
  3. Quadruple test
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5
Q

what is the combined test?

A

performed between 11-14w gestation

US + beta-HCG + PAPPA

US: Down’s if nuchal thickness >6mm

beta-HCG: higher result indicates a greater risk

Pregnancy-associated plasma protein-A: lower result indicates a greater risk

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6
Q

what is the triple test

A

performed between 14-20w gestation

Beta-HCG: higher result indicates a greater risk

Alpha-fetoprotein: lower result indicates a greater risk

Serum oestriol: lower result indicates a greater risk

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7
Q

what is the quadruple test?

A

performed between 14-20w gestation

Beta-HCG + AFP + serum oestriol + inhibin-A

inhibin-A: higher result indicates a greater risk

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8
Q

what is offered if the risk score for the fetus having Down’s syndrome is > 1 in 150

A

the woman is offered amniocentesis or chorionic villus sampling

this involves taking a sample of the fetal cells –> karyotyping

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9
Q

what does chorionic villus sampling involve?

A

an US guided biopsy of the placental tissue

done before 15w

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10
Q

what does amniocentesis involve?

A

US guided aspiration of some amniotic fluid using a needle + syringe

this is done after 15w once there is enough amniotic fluid to make it safer to take a sample

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11
Q

what is non-invasive prenatal testing (NIPT)?

A

gradually being rolled out in the NHS. Not definitive test but gives good indication of whether fetus is affected.

blood test from mother. DNA fragments analysed, some of which will come from the placental tissue and represent the fetal DNA

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12
Q

Mnx of Down’s

A

involve members of the MDT:

  • occupational therapy
  • speech + language
  • physio
  • dietician
  • paediatrician
  • GP
  • health visitors
  • cardiologist
  • ENT
  • audiologist
  • optician
  • social services
  • additional support w/ education needs
  • charity: Down’s Syndrome Association
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13
Q

name 4 routine follow up investigations that are important for children with Down’s syndrome

A

1) 2-yearly thyroid checks
2) echocardiogram: cardiac defects
3) audiometry
4) eye checks

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14
Q

what is the average life expectancy for someone with Down’s syndrome

A

60 years

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15
Q

what is Klinefelter syndrome

A

occurs when a male has an additional X chromosome making them 47 XXY

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16
Q

features of Klinefelter syndrome

A

males appear normal until puberty:

  • taller height
  • wider hips
  • gynaecomastia
  • weaker muscles
  • small testicles
  • reduced libido
  • shyness
  • infertility
  • subtle learning difficulties (esp affecting speech + language)
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17
Q

mnx options for Klinefelter syndrome

A
  • testosterone injections
  • advanced IVF techniques: have the potential to allow fertility
  • breast reduction surgery

MDT:

  • speech + language therapy
  • occupational therapy
  • physiotherapy
  • educational support
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18
Q

In Klinefelter syndrome there is a slight increased risk of? (4)

A
  • breast cancer compared with other males
  • osteoporosis
  • diabetes
  • anxiety + depression
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19
Q

What is Turner’s syndrome?

A

when a female has a single X chromosome making them 45XO

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20
Q

what are the 3 classic features in Turner’s syndrome?

A
  1. short stature
  2. webbed neck
  3. widely spaced nipples
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21
Q

name the features of Turner’s syndrome? (9)

A
  1. short stature
  2. webbed neck
  3. widely spaced nipples
  4. high arching palate
  5. downward sloping eyes w/ ptosis
  6. cubitus valgus
  7. underdeveloped ovaries w/ reduced function
  8. late or incomplete puberty
  9. most women are infertile
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22
Q

Turner’s syndrome

what is cubitus valgus

A

abnormal feature of the elbow

when the arm is extended downwards with the palms facing forward

the angle of the forearm at the elbow is exaggerated, angled away from the body

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23
Q

Turner’s syndrome

associated conditions (9)

A
  1. recurrent otitis media
  2. recurrent UTIs
  3. coarctation of the aorta
  4. hypothyroidism
  5. hypertension
  6. obesity
  7. diabetes
  8. osteoporosis
  9. various specific learning disabilities
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24
Q

Turner’s syndrome

management

A
  1. GH: to prevent short stature
  2. oestrogen + progesterone replacement: can help establish female secondary sex characteristics, regulate the menstrual cycle + prevent osteoporosis
  3. fertility trx: can increase chances of becoming pregnant
25
Q

Noonan Syndrome

inheritance pattern

A

autosomal dominant

26
Q

Noonan Syndrome

features (8)

A
  1. short stature
  2. broad forehead
  3. downward sloping eyes w/ ptosis
  4. Hypertelorism: wide space between the eyes
  5. prominent nasolabial folds
  6. low set ears
  7. webbed neck
  8. widely spaced nipples
27
Q

Noonan Syndrome

Associated conditions (6)

A
  1. congenital heart disease (pulmonary valve stenosis, hypertrophic cardiomyopathy, ASD)
  2. Cryptorchidism (undescended testes) –> infertility. Fertility normal in women
  3. learning disability
  4. bleeding disorders
  5. lymphoedema
  6. increased risk of leukaemia + neuroblastoma
28
Q

Noonan Syndrome

Management

A

supportive w/ MDT

the main complication is congenital heart disease and patients will require corrective heart surgery

29
Q

Marfan Syndrome

inheritance pattern

A

autosomal dominant condition affecting the gene responsible for creating fibrillin

30
Q

Marfan Syndrome

what is fibrillin?

A

an important component of connective tissue resulting in features of abnormal connective tissue

31
Q

Marfan Syndrome

features (8)

A
  1. tall stature
  2. long neck
  3. long limbs
  4. arachnodactyly: long fingers
  5. high arch palate
  6. hypermobility
  7. pectus carinatum or pectus excavatum
  8. downward sloping palpable fissures
32
Q

Marfan Syndrome

test for arachnodactyly (long fingers)

A
  1. if thumb tip can go past opposite edge of hand

2. if finger and thumb overlap when wrapped around other wrist

33
Q

Marfan Syndrome

associated conditions (7)

A
  1. mitral or aortic regurgitation
  2. lens dislocation in the eye
  3. joint dislocations
  4. scoliosis of spine
  5. pneumothorax
  6. GOR
  7. aortic aneurysms
34
Q

Marfan Syndrome

management

A
  • surgical correction of cardiac complications

Aim: minimise BP + HR to minimise stress on the heart

  • lifestyle changes: avoid intense exercise + avoid caffeine
  • BB + angiotensin II receptor antagonists
  • carefully consider pregnancy as risk of aortic aneurysms

physio: strengthen joints + reduce symptoms arising from hypermobility

genetic counselling

monitor with yearly echo and ophthalmologist

35
Q

Fragile X Syndrome

cause

A

mutation in the FMR1 gene (fragile x mental retardation)

on the X chromosome

trinucleotide repeat disorder

36
Q

Fragile X Syndrome

what does the FMR1 gene code for?

A

the fragile X mental retardation protein

which plays a role in cognitive development in the brain

37
Q

Fragile X Syndrome

inheritance pattern

A

X-linked but unclear whether it is dominant or recessive

38
Q

Fragile X Syndrome

are males or females affected?

A

males are always affected

females can vary in how much they are affected

39
Q

Fragile X Syndrome

mother is phenotypically normal. 2 ways in which the child may have got Fragile X Syndrome

A
  1. child inherited the X chromosome from their mother

2. de novo (random) mutation

40
Q

Fragile X Syndrome

features (9)

A
  1. delay in speech + language development
  2. intellectual disability
  3. long, narrow face,
  4. large ears
  5. large testicles after puberty
  6. hypermobile joints (esp in hands)
  7. ADHD
  8. Autism
  9. Seizures
41
Q

Fragile X Syndrome

mnx

A

supportive:

- MDT to support the learning disability, manage autism + ADHD + treat seizures if they occur

42
Q

Fragile X Syndrome

life expectancy

A

similar to general population depending on associated disabilities + complications

43
Q

Prader-Willi Syndrome

cause

A

loss of functional genes on the proximal arm of Ch15

inherited from father

can be due to a deletion of this portion of the Ch or when both copies of Ch15 are inherited from the mother

44
Q

Prader-Willi Syndrome

key feature

A

constant insatiable hunger that leads to obesity

Katie Price’s son, Harvey

45
Q

Prader-Willi Syndrome

features (12)

A
  1. constant insatiable hunger –> obesity
  2. hypotonia as an infant
  3. mild-moderate learning disability
  4. hypogonadism
  5. fairer, soft skin prone to bruising
  6. mental health problems (esp anxiety)
  7. dysmorphic features
  8. narrow forehead
  9. almond shaped eyes
  10. strabismus
  11. thin upper lip
  12. downturned mouth
46
Q

Prader-Willi Syndrome

mnx

A
  • GH: improve muscle development + body composition
  • limit access to food by locking it
  • dieticians
  • education support, social workers, psychologists, physios, occupational therapists
47
Q

Angelman Syndrome

cause

A

loss of function of the UBE3A gene, specifically the copy of the gene that is inherited from the mother

caused by a deletion on Ch15, a specific mutation in this gene or where 2 copies of Ch15 are contributed by the father, with no copy from the mother

48
Q

Angelman Syndrome

3 key features

A
  • WIDELY SPACED TEETH
  • UNUSUAL FASCINATION W/ WATER
  • HAPPY DEMEANOUR
49
Q

Angelman Syndrome

other features (14)

A
  • delayed development + learning disability
  • severe delay or absence of speech development
  • ataxia
  • inappropriate laughter
  • hand flapping
  • abnormal sleep patterns
  • epilepsy
  • ADHD
  • dysmorphic features
  • microcephaly
  • fair skin, light hair + blue eyes
  • wide mouth with widely spaced teeth
50
Q

Angelman Syndrome

Mnx

A

MDT:

  • parental education
  • social services + support
  • educational support
  • physio
  • occupational therapy
  • psychology
  • CAMHS
  • anti-epileptic medication where required
51
Q

difference between Prader Willi and Angelman syndrome

A

Prader WIlli is inherited from dad

Angelman is inherited from mother

52
Q

William Syndrome

cause

A

deletion of genetic material on one copy of Ch7

usually result of a random deletion around conception, rather than being inherited from an affected parent

53
Q

William Syndrome

3 key features

A
  • starburst eyes
  • very sociable trusting personality
  • wide mouth with a big smile
54
Q

William Syndrome

features

A
  • broad forehead
  • starburst eyes
  • flattened nasal bridge
  • long philtrum
  • wide mouth w/ widely spaced teeth
  • small chin
  • v.sociable trusting personality
  • mild learning disability
55
Q

William Syndrome

associated conditions

A
  • supravalvular aortic stenosis
  • hypercalcaemia
  • ADHD
  • HTN
56
Q

William Syndrome

mnx

A

MDT

echo and BP monitoring to assess for aortic stenosis + HTN

low Ca diet may be required to control hypercalcaemia

57
Q

which conditions is oesophagheal atresia more common in

A

trisomies – Downs/Pataus/Edwards

58
Q

why does oesophagheal atresia present with polyhydramnios

A

As the oesophagus is blind-ending, fluid cannot pass through the baby to be absorbed. This results in an accumulation of fluid outside the baby

59
Q

presentation of oesophagheal atresia

A

problems with swallowing. The baby will have difficulty feeding and has overflow saliva.