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PAEDIATRICS > GENETIC CONDITIONS > Flashcards

GENETIC CONDITIONS Flashcards

1
Q

Chromosome disorders: TRISOMY

A

= where the person has an extra chromosome, 3 copies of a particular chromosome
Total of 47 chromosomes

PATAU SYNDROME = trisomy 13

  • dysmorphic features, structural abnormalities affecting almost all areas of their body, learning disability
  • characteristic “rocker bottom feet” where the soles are covex (rounded outwards) in shape

EDWARDS SYNDROME = trisomy 18

  • dysmorphic features and learning disability
  • also “rocker bottom” feet

DOWNS SYNDROME = trisomy 21
- most common trisomy condition

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2
Q

Chromosome disorders: Duplication

A

E.g. Charcot-Marie-Tooth

  • duplication of short arm of chromosome 17
  • sensory and motor neuropathy and characteristic pes cavus (high arching foot)
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3
Q

Mitochondrial inheritance

A

Mitochondria comes from mother

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4
Q

Genetic testing

A

DIAGNOSTIC TESTING: Test a foetus vis amniocentesis
PREDICTIVE TESTING: testing for a specific gene mutation that has implications for them in the future e.g. BRACA1, Huntington’s chorea
CARRIER TESTING: testing for autosomal recessive conditions to calculate risk of passing it to their children

KARYOTYPING: looking at number of chromosomes, their size and basic structure
MICROARRAY TESTING
SPECIFIC GENE TESTING
DNA SEQUENCING (only used for research not clinical)

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5
Q

Down’s syndrome: Dysmorphic Features

A
  • Hypotonia
  • Brachycephaly (small head with a flat back)
  • Short neck
  • Short stature
  • Flattened face and nose
  • Prominent epicanthic folds (skin covering medial portion of the eye and eyelid)
  • upwards sloping palpable fissures (gaps between lower and upper eyelids)
  • single palmar crease
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6
Q

Down’s syndrome: Complications

A

Learning disability
Recurrent otitis media
Deafness
Eustachian tube abnormalities —> glue ear and conductive hearing loss
Visual problems (e.g. myopia, strabismus, cataracts)
Hypothyroidism (10-20%)
Cardiac defects (1 in 3) - particularly ASD, VSD, PDA, ToF
Atlantoaxial instability
Leukaemia is more common in those with downs
Dementia is more common in adults with downs

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7
Q

Down’s syndrome screening: Combined test

A

COMBINED TEST - first line most accurate test

  • between 11-14 weeks gestation
  • involves combing results from ultrasound and maternal blood tests
  • USS measures nuchal translucency (thickness of back of the neck of foetus)
  • MATERNAL BLOOD TEST
    - Beta-human chorionic gonadotrophin (Beta-HCG): higher result = greater risk
    - Pregnancy-associated plasma protein-A (PAPPA): lower result = greater risk
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8
Q

Down’s syndrome screening: Triple and quadruple tests

A

TRIPLE TEST
Performed between 14 and 20 weeks
Only involves maternal blood test results
- Beta HCG: higher = greater risk
- Alpha-fetoprotein (AFP): Lower = greater risk
- Serum oestriol (female sex hormone): lower = greater risk

QUADRUPLE TEST
Same as above but also includes maternal test for inhibin-A (higher=greater risk)

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9
Q

Down’s syndrome antenatal testing

A

If high risk score, mother offered:

AMNIOCENTESIS - US guided aspiration of amniotic fluid using a needle and syringe. Later on in pregnancy once there is enough amniotic fluid to take sample

Or

CHORIONIC VILLUS SAMPLING (CVS) - US guided biopsy of the placental tissue. Used earlier in pregnancy BEFORE 15 WEEKS

Sample of foetal cells undergo KARYOTYPING

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10
Q

Non-invasive prenatal testing

A

Relatively new test for detecting abnormalities in the foetus during pregnancy
Blood test from mother
Fragments of DNA from placental tissue contained in blood sample - represent fetal DNA
Fragments analysed and detect conditions such as downs
Not a definitive test but gives good indication

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11
Q

Down’s syndrome: Routine follow up investigations

A

Regular thyroid checks
ECG for cardiac defects
Regular audiometry for hearing impairment
Regular eye checks

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12
Q

Klinefelter Syndrome: genetics

A

ADDITIONAL X CHROMOSOME (47 XXY)

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13
Q

Klinefelter Syndrome: Features

A

Usually appear as normal males until puberty, at puberty:

  • Taller height
  • wider hips
  • gynaecomastia
  • weaker muscles
  • Small testicles
  • reduced libido
  • shyness
  • infertility
  • subtle learning difficulties
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14
Q

Klinefelter Syndrome: management

A

Can’t correct it, aim is to help the features

Testosterone injections
Advanced IVF treatment - has potential to allow fertility
Breast reduction surgery

MDT input (SALT, OT, PT, educational support)

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15
Q

Turners syndrome: Genetics

A

SINGLE X CHROMOSOME

45 XO

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16
Q

Turners syndrome: features

A

Short stature **
Webbed neck **
High arching palate
Downward sloping eyes with pots is
Broad chest with widely spaced nipples **
Cubits valgus (abnormal feature of elbow)
Underdevelopment of ovaries with reduced function
Late or incomplete puberty
Most females infertile

17
Q

Turners syndrome: associated conditions

A 
Recurrent otitis media 
Recurrent UTIs
Coarctation of the aorta 
Hypothyroidism 
Hypertension 
Obesity 
Diabetes 
Osteoporosis 
Various specific learning disabilities
18
Q

Turners syndrome: Treatment

A

Treatment not to cure, is to help with symptoms

Growth hormone therapy
Oestrogen and progesterone replacement
Fertility treatment

19
Q

Noonan syndrome: features

A 
Short stature 
Broad forehead 
Downward sloping eyes with pots is 
Hypertelorism (wide space between the eyes) 
Prominent nasolabial folds 
Low set ears 
Webbed neck 
Widely spaced nipples
20
Q

Noonan syndrome: Associated conditions

A

Congenital heart disease - particularly pulmonary valve stenosis, hypertrophic cardiomyopathy, ASD
Cryptorchidism (undescended testes) can lead to infertility (fertility normal in women)
Learning disability
Bleeding disorders
Lymphoedema
Increased risk of leukaemia and neuroblastoma

21
Q

Marfan syndrome: Genetic deficits

A

Autosomal dominant

Affects gene responsible for creating FIBRILLIN (an important component of CT)

22
Q

Marfans syndrome features

A 
Tall stature 
Long neck 
Long limbs 
Long fingers (arachnodactyly) 
High arch palate 
Hypermobility 
Pectus carinatum or pacts excavatum 
Downward sloping palpable fissures
23
Q

Tests for arachnodactyly

A
  1. ask them to cross their thumb across their palm - if the thumb tip goes past the opposite edge of the hand this indicates arachnodactyly
  2. Wrap thumb and finger of one hand around the other wrist, if the thumb and fingers overlap this also indicates arachnodactyly
24
Q

Marfans syndrome: Cardiac associations

A

Mitral valve prolapse (with regurgitation)
Aortic valve prolapse (with regurgitation)
Aortic aneurysms

Murmur: mitral regurgitation, aortic regurgitation

25
Q

Marfans syndrome: other associated conditions

A 
Lens dislocation in the eye 
Joint dislocations and pain due to hypermobility 
Scoliosis of the spine 
Pneumothorax
GORD
26
Q

Marfans syndrome: Management

A

Greatest risk = cardiac complications (valve prolapse and aortic aneurysms)
- may require surgical correction

Minimise BP and HR to minimise stress on the heart and risk of complications developing

  1. Lifestyle changes (avoiding intense exercise, caffeine and other stimulants)
  2. Preventative medications (e.g. beta-blockers, Angiotension II receptor antagonists)

Pregnancy carefully considered - as it carry’s significant risk of developing aortic aneurysms and associated complications

PHYSIOTHERAPY - to strengthen joins and reduce symptoms arising from hypermobility

GENETIC COUNSELLING

Regular follow up - ECG, ophthalmologist

27
Q

Fragile X syndrome mutation

A

Mutation in FMR1 (fragile X mental retardation 1) gene on the X chromosome

This gene codes for the fragile X mental retardation protein, which plays a role in cognitive development in the brain

Males always affected, but females can vary with how much they are affected (unclear whether dominant or recessive)

28
Q

Fragile X syndrome: features

A 
Delay in speech and language development 
Intellectual disability 
Long, narrow face
Large ears 
Large testicles after puberty 
Hyper mobile joints (particularly the hands) 
ADHD 
Autism 
Seizures
29
Q

Fragile X syndrome: Management

A

No cure
Supportive management and treat symptoms
MDT - support LD, manage autism and ADHD, treat seizures

30
Q

Prada-Willi Syndrome: Features

A 
Constant, insatiable hunger that leads to obesity ** 
Poor muscle tone as an infant (hypotonia) 
Mild-Moderate learning disability 
Hypogonadism 
Fair, soft skin, prone to bruising
Mental health problems, particularly anxiety 
Dysmorphic features
Narrow forehead 
Almond shaped eyes 
Strabismus 
Thin upper lip 
Downturned mouth
31
Q

Prada-willi syndrome: Management

A

No cure

Limit access to food under guidance of a dietician (lock on fridge etc)
Lower than normal calorie intake as they usually do less activity due to poor muscle strength and tone

Growth hormone - improving muscle development and body composition

MDT - dieticians, educational support, social workers, physiotherapists, occupational therapists

32
Q

Angelman syndrome mutation

A

UBE3A gene (deletion on chromosome mutation)

Specifically the gene inherited from the mother

33
Q

Angelman syndrome: Features

A 
Delayed development and learning disability 
Severe delay or absence of speech development 
Coordination and balance problems (ataxia) 
Fascination with water **
Happy Demeanour **
Inappropriate laughter 
Hand flapping 
Abnormal sleep patterns 
Epilepsy 
ADHD 
Dysmorphic features 
Microcephaly 
Fair skin, light hair, blue eyes 
Wide mouth and widely spaced teeth **
34
Q

Williams syndrome: features

A 
Broad forehead 
Starburst eyes (star like pattern on the iris) **
Flattened nasal bridge 
Long philtrum 
Wide mouth and widely spaced teeth **
Small chin 
Very sociable trusting person **
Mild LD
35
Q

Williams syndrome associations

A

Supravalvular aortic stenosis (narrowing just above the aortic valve)
Hypercalcaemia

Hypertension
ADHD

36
Q

Williams syndrome: Management

A

No cure, managment = MDT approach

ECG and blood pressure monitoring (assess for aortic stenosis and hypertension)
Low calcium diet - avoid calcium and vitD supplements

PAEDIATRICS (18 decks)

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