Down Flashcards
What Characterizes Complete Trisomy 21?
The Most Common
Complete Trisomy 21
- Karyotyping
47,XX + 21
Incidence of Complete Trisomy 21
What Is Complete Trisomy 21 dependent on?
Maternal Age
Cause of Complete Trisomy 21
- Non-disjunction of chromosome 21 during meiotic division (80 % in maternal meiosis I)
- lt occurs during oogenesis more than spermatogenesis.
Mosaic Down Syndrome
- Karyotyping
47, XX + 21 / 46, XX
Translocation Down Syndrome
- Karyotyping
46,XX, t(14q, 21q)
D/21 Translocation
- lf ovum contains translocation chromosome only, fertilization by normal sperm will Iead to …..
BTC —> (45 chromosome but genome of 46 chromosomes)
- lf ovum contains translocation chromosome and normal chromosome 21, fertilization by normal sperm will lead to …..
Down syndrome (46 chromosome but genome of 47 chromosomes)
G/21 Translocation
Down Syndrome
- Constant Features
- Delayed physical growth
- Delayed mental development (mild to moderate mentaI retardation)
- Hypotonia
CP of Down Syndrome
- Head
CP of Down Syndrome
- Eyes
CP of Down Syndrome
- Nose
Small with depressed nasal bridge
CP of Down Syndrome
- Ears
- Small
- Low set & backward displacement
CP of Down Syndrome
- Neck
Short & Webbed
CP of Down Syndrome
- Tongue
- Protruded (small oral cavity)
- Fissured (scrotal)
CP of Down Syndrome
- Ribs
Unilateral or bilateral absence of one rib
CP of Down Syndrome
- Hands
Def of Brachydactyly
Short + stocky
Def of Clinodactyly
lncurved little fingers
- Due to rudimentary or absent mid phalanx of
little finger)。
Def of Simian Crease
Transverse palmer crease (partial or complete)
CP of Down Syndrome
- Feet
CP of Down Syndrome
- GIT & Abdomen
CP of Down Syndrome
- CoHD
CP of Down Syndrome
- Endocrine
CP of Down Syndrome
- Genitalia
Poorly developed
CP of Down Syndrome
- Immunity
Impaired cellular & humeral immunity
Complications of Down Syndrome
Most Common Causes of Death Down Syndrome
- Accidents due to mental retardation
- Sudden death due to arrhythmia
Most Common Presentation of complication Down Syndrome
- 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)
INVx for Down Syndrome
- Prenatal
- After Birth
INVx for Down Syndrome
- Prenatal Dx
INVx for Down Syndrome
- Prenatal Dx (1st Trimester)
INVx for Down Syndrome
- Prenatal Dx (2nd Trimester)
Maternal Serum Screening in 2nd Trimester for Down Syndrome
INVx for Down Syndrome
- After Birth
DDx of Down Syndrome
Managment Plan for Down Syndrome
Genetic Counseling for Down Syndrome