Down's syndrome Flashcards

1
Q

Define Down’s syndrome

A

A form of intellectual disability caused by trisomy 21, which results in characteristic physical features, short stature, cognitive and behavioural profiles, as well as a higher frequency of associated medical conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the aetiology of Down’s syndrome

A

Meiotic non-disjunction or failure of chromosome pairs to separate during gamete formation → trisomy 21 (no need to check parental Chr)
4% have Robertsonian translocation between 21q and the long arm of the other acrocentric chromosome (check parental Chr - risk of recurrence)
1% have mosaic type

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the risk factors for Down’s syndrome

A

Increasing maternal age (1 in 1000 <30 years, 1 in 100 aged 40, 1 in 12 aged 49)
Sibling with Down’s syndrome (chance 1 in 100)
Abnormal parental karyotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the symptoms of Down’s syndrome

A

Typically diagnosed as a newborn due to the characteristic physical presentation

  • Cognitive disability: visuo-spatial tasks, IQ range from mild-moderate ID
  • Developmental delay (expressive language)
  • Hearing loss (chronic ear infections)
  • ASD
  • Congenital GI disorders e.g. duodenal/anal stenosis/atresia
  • Constipation
  • Feeding difficulties e.g difficulty sucking or coordinating feeding (Hypotonia, underweight, slow/choking feeds, recurrent/persistent resp/ symptoms, desaturation with feeding)
  • Behavioural difficulties, especially with peers
  • Social and affectionate
  • Characteristic physical features
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the characteristic physical features of Down’s syndrome

A

Flat face and occiput
Epicanthal folds
Upslanting palpebral fissure
Brushfield spots on irirs
Short nose, low nasal bridge, small nares (nostrils)
Round cheeks
Small ears, may be low-set
Protruding tongue, small mouth
Broad neck, extra skin
Single palmar crease, short hands, fifth finger clinodactyly
Wide sandal gap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the differentials for Down’s syndrome

A

Isolated hypotonia
Zellweger’s syndrome (hypotonia, flat occiput and face, epicanthal folds, brushfield spots, cataracts, seizures, single palmar crease, NORMAL karyotype)
Congenital hypothryoidism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What investigations should be done for Down’s syndrome

A

Bloods
- Chromosomal karyotype: trisomy 21/Robertsonian translocation/mosaicism
- FBC: normal/abnormal (screen for TAM)
- TFTs: Normal (exclude hypothyroidism)
Other: echocardiogram, hearing tests, visual examination, AXR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the management for Down’s syndrome

A
  1. Immediate assessment ± specialist consult for any medical conditions
    - Echo
    - Genetic counselling
    - Early intervention for delay: PT, OT, SALT

Refer to child development services
- Regular review of development and health
- Liaise with schools → individualised educational plan
- Screen periodically (annually up to 5yo, then every 2 years): vision, hearing, TFTs, coeliac, atlantoaxial instability, Hb (IDA), sleep apnoea, growth

Resources: Down syndrome association, National down syndrome society

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is Down’s syndrome screened for in pregnancy

A

All pregnant women are offered the combined test at 11-13+6 week
Triple test: ↑Nuchal translucency + ↑serum b-hCG + PAPP-A (pregnancy associated plasma protein A)
Quadruple (for those booking later, 15-20 weeks: ↓Alpha-fetoprotein + ↓unconjugated oestriol + ↑HCG + ↑inhibin A

→ if high chance (<1 in 150) → diagnostic test (cell-free foetal DNA, amniocentesis, Chorionic villus sampling)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the complications of Down’s syndrome

A

Congenital heart defects: tetralogy of fallot, atrio-ventricular septal defect, ASD/VSD
GI: Duodenal atresia, Hirschprung’s disease, coeliac disease, Omphalocoele ± umbilical hernia
Hypothyroidism
Leukaemia and solid tumours (Transient abnormal myelopoiesis/AML)
Obstructive sleep apnoea
Audiological: otitis media, hearing impairment
Visual: congenital cataracts, strabisimus, myopia/hyperopia, blepharitis
Early onset alzheimer’s
Atlantoaxial instability: screen in those who participate in sports that may carry an increased risk of neck dislocation e.g. trampolining, gymnastics, boxing, diving, rugby horse riding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the prognosis for Down’s syndrome

A

Difficult to predict long-term prognosis in the neonatal period
Congenital heart disease is a major cause of early mortality
Over 85% of infants with trisomy 21 survive to 1 year of age
At least 50% of individuals live longer than 50 years in the UK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly