L2: Down Syndrome

Question 1

Epidemeology of Down Syndrome

Answer 1

Question 2

Def & Results of Meiosis

Answer 2

Question 3

Cytogenic Types of Down Syndrome

Answer 3

• Complete Trisomy 21
• Mosaic Down Syndrome
• Translocation Down Syndrome

Question 4

What Characterizes Complete Trisomy 21?

Answer 4

The Most Common

Question 5

Complete Trisomy 21

• Karyotyping

Answer 5

47,XX + 21

Question 6

Incidence of Complete Trisomy 21

Answer 6

Question 7

What Is Complete Trisomy 21 dependent on?

Answer 7

Maternal Age

Question 8

Cause of Complete Trisomy 21

Answer 8

• Non-disjunction of chromosome 21 during meiotic division (80 % in maternal meiosis I)
• lt occurs during oogenesis more than spermatogenesis.

Question 9

Risk of Recurrence in Complete Trisomy 21

Answer 9

1-2% regardless of maternal age

Question 10

What Characterizes Mosaic Down Syndrome?

Answer 10

The Best Type

Question 11

Mosaic Down Syndrome

• Karyotyping

Answer 11

47, XX + 21 / 46, XX

Question 12

Incidence of Mosaic Down Syndrome

Answer 12

1-2% of cases (more with maternal age)

Question 13

Cause of Mosaic Down Syndrome

Answer 13

• Non-disiunction occurring early in the division of the zygote, which results in two lines of cells (normal & trisomic)

Question 14

Risk of Recurrence i Mosaic Down Syndrome

Answer 14

Same as Complete

Question 15

Clinical manifestations in mosaic type are ….. than complete trisomy

Answer 15

Iess

Question 16

• ln mosaic type, non-disjunction occurs during …. division
• while in complete type, it occurs during …. division

Answer 16

• mitotic
• Meiotic

Question 17

What Characterizes Translocation Down Syndrome?

Answer 17

The Most Serious Type

Question 18

Translocation Down Syndrome

• Karyotyping

Answer 18

46,XX, t(14q, 21q)

Question 19

Incidence of Translocation Down Syndrome

Answer 19

o lncidence 3- 4%
o Common in young age < 25 years

o Robertsonian translocation is the most common type

Question 20

……. translocation is the most common type

Answer 20

Robertsonian

Question 21

Cause of Translocation Down Syndrome

Question 22

Risk of Recurrence in Translocation Down Syndrome

Answer 22

Question 23

Types of inherited Translocation

Answer 23

• D/21 Translocation
• G/21 Translocation

Question 24

D/21 Translocation

Answer 24

Question 25

- lf ovum contains translocation chromosome only, fertilization by normal sperm will Iead to .....

Answer 25

BTC ---> (45 chromosome but genome of 46 chromosomes)

Question 26

- lf ovum contains translocation chromosome and normal chromosome 21, fertilization by normal sperm will lead to .....

Answer 26

Down syndrome (46 chromosome but genome of 47 chromosomes)

Question 27

G/21 Translocation

Answer 27

Question 28

Pathogenesis of **Down Syndrome**

Answer 28

Question 29

CP of **Down Syndrome**

Answer 29

A LOTTTTTTT

Question 30

**Down Syndrome** - Constant Features

Answer 30

- Delayed physical growth - Delayed mental development (mild to moderate mentaI retardation) - Hypotonia

Question 31

CP of **Down Syndrome** - Head

Answer 31

Question 32

CP of **Down Syndrome** - Eyes

Answer 32

Question 33

CP of **Down Syndrome** - Nose

Answer 33

Small with depressed nasal bridge

Question 34

CP of **Down Syndrome** - Ears

Answer 34

- Small - Low set & backward displacement

Question 35

CP of **Down Syndrome** - Neck

Answer 35

Short & Webbed

Question 36

CP of **Down Syndrome** - Tongue

Answer 36

- Protruded (small oral cavity) - Fissured (scrotal)

Question 37

CP of **Down Syndrome** - Ribs

Answer 37

Unilateral or bilateral absence of one rib

Question 38

CP of **Down Syndrome** - Hands

Answer 38

Question 39

Def of **Brachydactyly**

Answer 39

Short + stocky

Question 40

Def of **Clinodactyly**

Answer 40

lncurved little fingers - Due to rudimentary or absent mid phalanx of little finger)。

Question 41

Def of **Simian Crease**

Answer 41

Transverse palmer crease (partial or complete)

Question 42

CP of **Down Syndrome** - Feet

Answer 42

Question 43

CP of **Down Syndrome** - GIT & Abdomen

Answer 43

Question 44

CP of **Down Syndrome** - CoHD

Answer 44

Question 45

CP of **Down Syndrome** - Endocrine

Answer 45

Question 46

CP of **Down Syndrome** - Genitalia

Answer 46

Poorly developed

Question 47

CP of **Down Syndrome** - Immunity

Answer 47

Impaired cellular & humeral immunity

Question 48

Complications of **Down Syndrome**

Answer 48

Question 49

Most Common Causes of Death **Down Syndrome**

Answer 49

- Accidents due to mental retardation - Sudden death due to arrhythmia

Question 50

Most Common Presentation of complication **Down Syndrome**

Answer 50

- Heart failure due to congenital heart disease - Recurrent chest infections due to CHD, i immunity, most common presentation Hypotonia, aspiration & Decreased immunity **(Predominantly T cell dysfunction, however, both T & B cells functions are affected)**

Question 51

INVx for **Down Syndrome**

Answer 51

- Prenatal - After Birth

Question 52

INVx for **Down Syndrome** - Prenatal Dx

Answer 52

Question 53

INVx for **Down Syndrome** - Prenatal Dx (1st Trimester)

Answer 53

Question 54

INVx for **Down Syndrome** - Prenatal Dx (2nd Trimester)

Answer 54

Question 55

Maternal Serum Screening in 2nd Trimester for **Down Syndrome**

Answer 55

Question 56

INVx for **Down Syndrome** - After Birth

Answer 56

Question 57

DDx of **Down Syndrome**

Answer 57

Question 58

Managment Plan for **Down Syndrome**

Answer 58

Question 59

Genetic Counseling for **Down Syndrome**

Answer 59

Question 60

Risk of Recurrencre in **Down Syndrome**

Answer 60