2 Deletion (DiGeorge Syndrome)

Dec 27, 2018 by in OBSTETRICS Comments Off on 2 Deletion (DiGeorge Syndrome)

KEY POINTS Print Section Listen Key Points Most common microdeletion syndrome reported in humans. 22q11.2 deletion is associated with DiGeorge syndrome, velocardiofacial syndrome (VCFS), Opitz G/BBB syndrome, and Cayler cardiofacial…

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Trisomy 21 (Down Syndrome)

Dec 27, 2018 by in OBSTETRICS Comments Off on Trisomy 21 (Down Syndrome)

KEY POINTS Print Section Listen Key Points Ninety percent of individuals with Down syndrome have three full copies of chromosome 21. Three to 4% have an unbalanced translocation, and 1%…

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Triploidy

Dec 27, 2018 by in OBSTETRICS Comments Off on Triploidy

KEY POINTS Print Section Listen Key Points Occurs in 1% to 2% of clinically recognized conceptions but only 1/10,000 livebirths. Not associated with advanced maternal age. Most cases are 69,…

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X (Turner Syndrome)

Dec 27, 2018 by in OBSTETRICS Comments Off on X (Turner Syndrome)

KEY POINTS Print Section Listen Key Points Most common chromosomal abnormality that occurs in females. Only 1%of conceptuses with Turner syndrome survive to term. Incidence is 1 in 2500 female…

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Other Autosomal Aneuploidies

Dec 27, 2018 by in OBSTETRICS Comments Off on Other Autosomal Aneuploidies

KEY POINTS Print Section Listen Key Points Trisomies 8,9,14,16, and 20, if present in mosaic form, are compatible with postnatal survival. Mosaic trisomies are generally associated with nondisjunction due to…

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XYY

Dec 27, 2018 by in OBSTETRICS Comments Off on XYY

KEY POINTS Print Section Listen Key Points Incidence is 1 in 1000 males. Most cases are undiagnosed. Not associated with advanced parental age. There are no characteristic fetal sonographic findings….

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XXX (Triple X Syndrome, Trisomy X)

Dec 27, 2018 by in OBSTETRICS Comments Off on XXX (Triple X Syndrome, Trisomy X)

KEY POINTS Print Section Listen Key Points Incidence is 1 in 1000 females. Most cases are undiagnosed. Associated with advanced maternal age (70% are due to a meiosis I error)….

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(Klinefelter Syndrome)

Dec 27, 2018 by in OBSTETRICS Comments Off on (Klinefelter Syndrome)

KEY POINTS Print Section Listen Key Points Results from meiotic nondisjunction that occurs in the sperm (44% of cases) or egg (56% of cases). About 10% of all cases are…

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Trisomy 18

Dec 27, 2018 by in OBSTETRICS Comments Off on Trisomy 18

KEY POINTS Print Section Listen Key Points Second most common autosomal trisomy in liveborn infants. Eighty to 85% of cases result from full trisomy, 10% are mosaics, and 5% are…

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