Trisomy 13 - Trisomy 13 The incidence is about 1 in 5000...

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Trisomy 13 The incidence is about 1 in 5000 live births. 50% of these babies die within the first month and very few survive beyond the first year. There are multiple dysmorphic features. Most cases, as in Down's syndrome, involve maternal non-disjunction. Again, a significant fraction have a parent who is a translocation carrier. Trisomy 18 (Edward's syndrome) Incidence ~1 in 3000. Again most babies die in the first year and many within the first month. sex chromosome aneuploidies Because of X inactivation and because of the paucity of genes on the Y chromosome, aneuploidies involving the sex chromosomes are far more common than those involving autosomes. o Turner syndrome, 45, X The incidence is about 1 in 500 female births but this is only the tip of the iceberg, 99% of Turner syndrome embryos are spontaneously aborted. Individuals are very short, they are usually infertile. Characteristic body shape changes include a broad chest with widely
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Trisomy 13 - Trisomy 13 The incidence is about 1 in 5000...

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