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What are risk factors of trisomies?
- maternal age
- previous child
- exposure to radiation/mutagenic drug
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What is hypotoni
- eventually resolves--> tend to be short
- mouth open and tongue protrudes
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What is the most common chromosomal abnormality?
Trisomy 21
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What are some symptoms of Trisomy 21
- faces are flattened
- epicanthic folds
- gaps between toes
- brushfold spots on iris
- cardiac/gastro malformations
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What is considered as mental retardation?
- 30-60
- hearing problems
- leukemia
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What disease are they prone to as they get older?
- AD
- amyloid precursor protein (APP)
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What is clinodatyly?
pinkie finger is bent towards the finger
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What is etiology?
the reasons that abn occurs
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What are the 2 main chromo structures?
- 3 whole copies (95% of cases)
- 2 whole copies and a piece (how much) (translocation)
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What are the mechanisms for this to occur?
- non disjunction during gametogenesis (95%)
- maternal meiosis I (90%)
- paternal meiosis II (10%)
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What are the rare cases of T21?
- mosaicism (1-2%)
- have fewer phenotypic
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Translocation
- 46, XX or XY, 21 trans 14
- 4% of cases
- this is known as balanced translocation
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Who is at higher risk for having a Downs baby?
parent with Robertsonian
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What is the mutation of parents?
translocation parent [rob, 14;21]
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What are some screening test?
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What are definite ways to determine T21?
karyotype or FISH at birth
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What are other ways to see if T21?
- Screening test: blood test
- false normals
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What is found in sonograms?
- nuchal translucency (thickness of neck)
- shortened limbs
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What are some diagnostic test?
- chronic villus sampling
- percutaneous umbilical cord sampling
- amniocentesis
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What is trisomy 18 occurrence?
- 30: 10000 more in females
- <10% survival
- hypertonicity
- rocker bottom feet
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What is trisomy 13?
- >80% die in the first few months
- cleft lip/palate, microcephaly, cardiac, etc
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What is Cri du Chat?
- this is having a deletion of chromo 5
- mapping bands to the protein in that band
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What are the pheno in Cats cry syndrome?
hypertelorism, epicanthic folds
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