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Down syndrome (Complications (Neurological
Developmental delay
Learning…
Down syndrome
Complications
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Ocular
Visual impairment (cataract, squint, myopia)
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Pathophysiology
Translocation
Rare (5%)
Robertsonian translocation when acrocentric chromosomes
undergo unequal translocation; may be somatic or inherited
Ends up with Chr21 becoming attached to Chr 14 (15, 21, or 22)
If inherited, parent has 45 Chr but phenotypically normal, child is 46 Chr but phenotypically abnormal
Meiotic non-disjunction
Commonest cause (95%)
Error at meiosis in gamete, with one recieving 2 Chr 21
and other receives 3
Fertilisation causes trisomy 21
Related to maternal age, but can also be paternal
Mosaicism
VERY rare (1%)
Some of the patients cells are normal and some have trisomy 21
Meiosis and gamete formation occurs normally, but non-disunction at later meiotic cycles
Clinical
presentation
Face/head
Round face
Flat occiput, third fontanelle
Epicanthic folds of eyes
Brushfield spots of iris
Depressed nasal bridge
Small mouth, protruding tongue
Small ears
Short neck
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Management
Conservative
Information, advice, support
Referral to paediatrician
Regular health and development reviews
Screening for vision, hearing, hypothyroidism, coeliac disease
Screening
Antenatal screening programme
Trisomy blood tests
Foetal anomaly screening (nuchal thickness)
Amniocentesis (check karyotype)
Chorionic villous sampling
Cell free foetal DNA (becoming routine)