Down syndrome (Trisomy 21)
Down syndrome is a genetic disorder caused when abnormal cell division result in extra-genetic material from chromosome 21.
Down syndrome (Trisomy 21 - Extra genetic material from chromosome 21.
Individual with Down syndrome have 47 chromosomes in total instead of 46 number of chromosomes.
Types of Down Syndrome
1. Trisomy 21 (95%)
Extra 21 chromosomes present, total number of chromosomes are 47.
2. Translocation (3-4%)
A segment of 21 chromosome is found attached to other pairs of chromosome.
Etiology
1. Error in cell division (called Nondisjunction)
2. During meiosis error
3. Abnormal cell division (meiosis)
4. Inherited
5. Teratogens exposure
6. Chromosomal error
Risk Factors
1. Woman age 35 year or older age pregnancy
2. According to CDC, younger mother (<35 years) who smoke, use oral contraceptive, meiosis error
Clinical manifestation
1. Microcephaly
2. Flat face with upward slant to eye.
3. Short and wide neck
4. Flat nasal bridge
5. Protruding tongue
6. Small head, ear and mouth
7. Brush field spots (tiny white spots on iris of eyes).
8. Short broad hands and feet with single crease on the palm of their hands.
9. Small pinky fingers that sometimes curve towards thumb.
10. Excessive space between large toe and second toe.
11. Muscle hypotonia (weak muscle tone)
Complications
1. Mental retardation
2. Delayed language, social and motor development
3. Growth retardation
4. Congenital Heart disease
Atrial or Ventricular septal defect
5. Respiratory infection
Pneumonia
6. Vision problem; cataract
7. Hearing loss
8. Gastrointestinal blockage
9. Thyroid dysfunctional
10. Sleep apnea
11. Increase risk of Dementia
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