1. Year 10 Science Health and disease
Genetic disease:
Down’s syndrome
Chris Willocks 2007

2. Down’s Syndrome
What are some traits of Down’s syndrome?

3. Down’s syndrome

5. Down’s syndrome traits
low muscle tone
eyes may have an upward and outward slant
nasal bone can be underdeveloped
the tongue can have less space and protrude
legs and arms are often shorter
hands are short and stubby with a single crease across the palm
genitals may be small
hair is sometimes fine and straight
teeth may be slightly smaller and do not appear in normal ‘order’
delay in sitting, crawling, talking, toileting
most have mental retardation in the mild (IQ 50–70) to moderate (IQ 35–50) range
can have heart defects, digestive disorders etc

6. Down’s syndrome karyotype

7. Trisomy 21
Down syndrome disorders are based on having too many copies of the genes located on chromosome 21.
This leads to an overexpression of the genes

8. Incidence of Down syndrome
Occurs in all races
One in every 600 to 700 babies born
Probably more Down syndrome babies are conceived, but many miscarriages are due to a chromosome error
The number of children born with Down syndrome increases as mothers become older.

9. Effect of Mother’s age

10. Effect of mother's age
Mothers in their 40's are much more likely to have a child with Down's syndrome than younger mothers.
The eggs produced during ovulation are as old as the mother.
There is a greater chance for older eggs to have problems that lead to nondisjunction.
Younger mothers (<35 years) who smoke are at an increased risk of having children with Down syndrome.

12. Development in childhood
Development is variable
Delay in sitting, crawling, talking
It is not possible to predict their capabilities
Early intervention programs from birth are useful
Success at school can vary greatly
It is common for children with Down syndrome to need speech therapy to help with expressive language.
Fine motor skills are delayed and often lag behind gross motor skills

13. Intervention programs

14. Life span
The average life expectancy of a person with Down syndrome is 55+, with some people living into their 80's.
In % of children died before 5 years of age
Medical research has totally changed the quality of health of people with Down syndrome.

15. Relationships
People with Down syndrome have feelings just like anyone else in the community.
Respond to positive expressions of friendship
Are hurt and upset by inconsiderate behaviour.

16. Ageing parents
What happens to them as their parents age?

17. Sex and marriage
People with Down syndrome date, socialise and form on-going relationships
In the past it has been unusual for people with Down syndrome to marry
Females with Down syndrome menstruate and have been recorded as mothers. There is a 50% chance that their child will have Down syndrome.
A proportion of males who have Down syndrome will produce sperm and cannot be considered sterile.

18. Detecting Down’s
Ultrasound may detect abnormal foetal growth

19. Foetal development

20. Amniocentesis
Cells from the amniotic fluid are karyotyped