Genetics Flashcards
(48 cards)
Clinical features of Downs Syndrome
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Define congenital defect
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Subdivisions of congenital defects
- Single
- Multiple
Single congenital abnormalities
- Malformation
- Disruption
- Deformation
- Dysplasia
Multiple congenital abnormalities
- Sequence
- Syndrome
- Association
Malformation
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Disruption
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Deformation
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Dysplasia
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Syndrome
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Sequence
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Association
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Aneuploidy of Patau Syndrome
Trisomy 13
Aneuploidy of Edward’s Syndrome
Trisomy 18
Aneuploidy of Downs Syndrome
Trisomy 21
Clinical features of Downs Syndrome
Newborn: -hypotonia (floppy baby syndrome=decreased muscle tone) -lethargy -excess nuchal skin Craniofacial: -macroglossia (abnormally large tongue) -small ears -epicanthic folds (vertical fold of skin from the upper eyelid that covers the inner corner of the eye) -brushfield spots (tiny white spots around the iris of the eye) Cardiac: -septal defects -atrioventricular canal Limb: -single palmar crease -sandal gap (wide gap between the first and second toes) Other: -short stature -duodenal atresia -low IQ but advanced social skills
Three different chromosome aberrations leading to Downs Syndrome
1) Trisomy 21 (in 95% of cases)
2) Translocation (Robertsonian specifically and in 4% of all cases)
3) Mosaicism (1% of cases=abnormal cell population in the body)
Clinical features of Patau’s Syndrome
Brain problems: -Holopresencephaly (structural malformation of the brain which often affects facial features giving a cleft lip and orbital hypotelorism) -mental retardation Cardiac problems: -septal defects -patent ductal arteriosus
Clinical features of Edward’s Syndrome
Brain problems: -mental retardation Cardiac problems: -septal defects -patent ductal arteriosus Digestive tract defects: -Oesophageal atresia (upper part does not connect with lower part and stomach) -Omphalocele (infants intestine or other abdominal organs are outside the body because of a hole in the belly button area) Kidney malformations: -Horseshoe kidney
Example of autosomal dominant disorder
Huntington’s disease
Example of autosomal recessive disorder
Cystic fibrosis
Example of X-linked recessive disorder
Haemophilia
Prader-Willi Syndrome
- Chromosome 15 imprinting disorder
- paternal chromosome loses function (P=paternal)
Angelman Syndrome
- Chromosome 15 imprinting disorder
- maternal chromosome loses function
