DR Medhat MRCP

Later complications
1. Subfertility: males are almost always infertile due to impaired spermatogenesis.
Females are usually subfertile, and have an increased incidence of problems with
pregnancy and labour
2. Learning difficulties
3. Short stature
4. Repeated respiratory infections (+hearing impairment from glue ear)
5. Acute lymphoblastic leukaemia
6. Hypothyroidism
7. Alzheimer's
8. Atlantoaxial instability
• Risk of Down's syndrome with increasing maternal age
Risk at 30 years = 1/1000
35 years = 1/350
40 years = 1/100
45 years = 1/30
- One way of remembering this is by starting at 1/1,000 at 30 years and then dividing by
3 (i.e. 3 times more common) for every extra 5 years of age
- The chance of a further child with Down's syndrome is approximately 1 in100 if the
mother is less than 35 years old
- If the trisomy 21 is a result of a translocation the risk is much higher
• Cytogenetics :
Mode % of cases Risk of recurrence
Non-dysjunction 94% 1% if mother < 35 years
Robertsonian translocation
(usually onto 14)
Mosaicism 1%
5% 10-15% if mother is translocation carrier
2.5% if father is translocation carrier
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