Lecture 7 (deleted 4f50fb8f-1dc8ae-5a2a49fd)

Detects downs syndrome 81 of the 1me ultrasound

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Unformatted text preview: ase (genotype for common muta1ons) The quad screen test is a maternal blood screening test that looks for four specific substances: •  •  •  •  AFP: alpha ­fetoprotein is a protein that is produced by the fetus hCG: human chorionic gonadotropin is a hormone produced in the placenta Estriol: estriol is an estrogen produced by both the fetus and the placenta Inhibin ­A: inhibin ­A is a protein produced by the placenta and ovaries *successfully detects Down’s syndrome 81% of the 1me Ultrasound Maternal Blood screening Gene1c screening Prenatal Tes1ng for Gene1c Abnormali1es 9 Further Tes1ng? Advanced Maternal Age (AMA) Normal Atypical Abnormal Test results: blood or ultrasound 10 5 2/14/12 Chorionic villus sampling (CVS) Amniocentesis Invasive gene1c tes1ng Invasive approaches to harvest fetal cells for karyotyping 11 New methods: noninvasive fetal diagnosis 12 6 2/14/12 Karyotype of fetal DNA Fetal screening (via karyotype) can detect gross chromosomal abnormali1es and sex 13 Human sex chromosomes In mammals, the presence/absence of the Y determines sex 14 7 2/14/12 Sry = Sex ­determining Region on the Y chromosome Sry is a switch which ini1ates the male pathway; default pathway is female 15 Mammalian Gonadal Development Testosterone: promotes males characters An1 ­Mullerian hormone: reduces female traits Produc1on of androgens leads to sex organ differen1a1on 16 8 2/14/12 Androgen Insensi1vity Disclaimer: Jamie Lee Cur1s may or may not be androgen insensi1ve. Note: Supermodels have a higher frequency compared to the general popula1on. Sexual differen1a1on requires more than just sex chromosomes and SRY 17 Problem: If the X and Y chromosome are so different (e.g., size and gene content), how can they pair properly during meiosis? 18 9 2/14/12 Psuedo ­autosomal region (PAR) Note: PAR has one of the highest rate of recombina1on in the en1re genome Common region of X and Y pairs (and crosses over) during meiosis...
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