Down syndrome is a neurodevelopmental syndrome characterized by distinctive physical features and developmental delays. It is caused by the presence of an extra chromosome 21, either full trisomy 21 or partial trisomy. Common physical features include a short neck, small ears, a tongue that sticks out, small hands and feet, and a single crease across the palm. Individuals with Down syndrome may experience health issues such as heart defects, hearing loss, thyroid problems, celiac disease, seizures, and sleep apnea.

1. Down syndrome
By:
Fadel Adnan
Supervisor:
Dr. Ahmed Bashir

2. Down syndrome ?
• Neurodevelopmental
syndrome named for John
Langdon Haydon Down who
first described the physical
and behavioral characteristics
in 1862

3. • 1958 Jerome Lejeune and his team identified
trisomy 21 (47 chromosomes-one extra
chromosome 21 in cells) as cause of Down
Syndrome
• Only 2 years after it was discovered that the
typical number of human chromosomes was
46
Down syndrome

5. Non-disjunction cell
division-47 chromosomes
Typical cell division- 46
chromosomes

7. 90-95% full trisomy from nondisjunction of
maternal origin during meiosis
2-4% translocation
(usually 13-15 or 21-22)
2-4% mosaicism
nondisjunction occurs after fertilization
resulting in two different cell lines
Type of Down syndrome

8. A group of people with
Down syndrome

9.  A short neck
 Small ears
 A tongue that tends to stick out of the mouth
 Tiny white spots on the iris (colored part) of the eye
 Small hands and feet
 A single line across the palm of the hand (palmar crease)
 Poor muscle tone or loose joints
 Shorter in height as children and adults
common physical features of Down syndrome

10. Normal

11. Health in Down Syndrome
• Eyes: cataracts and glaucoma
5% Cataracts
1% Glaucoma
Near-sightedness
• Ears: hearing loss
_ 30-75% by preschool

12. Health in Down Syndrome
• Thyroid: low thyroid
_30% by 25 years
• Gut: celiac disease (wheat allergy)
_4-7%
• Immune dysfunction:
autoimmune/leukemia

13. Down Syndrome
• Brain:
_Seizures 8%-50% by 50 years
_Sleep apnea
_Developmental
delays/learning differences