Human Heredity and Development_Walsh_Date_030910

Human Heredity and Development_Walsh_Date_030910 - Types of...

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Types of Down syndrome 47, XX, +21 47, XY, +21 Cause: Not in meiosis Translocation 44, XX, + (4, 21) 5% of Down syndrome cases Inheritable o Can be run in family, related to parental age o Parents may be a carrier o Father is a balanced carrier o Phenotype: Robertsonian Mosaic – 46, XX/47,XX, +21 o Individual with 2 or more genetically different cell lines. One to two percent of Down syndrome cases Turner Syndrome Frequency: (45, X) or (45, XO) 99% of TS fetuses die in utero Absence of Y chromosome Absence of two copies of X-linked genes Numerical Abnormalities: Polypoidy and aneuploidy Need both X’s for normal birth Sometimes has hearing problems Sometimes doesn’t show up until after puberty Can hinder height Deletions of the P arm Mosaic – occurs in anaphase, meiosis and can occur in either parent but often the dad; 46XX/45X occurs in mitosis & early development or a choromosome lagging (anaphase lag) Isochromosomes Generally normal intelligence, growth hormones, some have given birth. Not that bad but normal phenotype needs 2 Xs Klinefelter Syndrome Frequency – 1 in 1000 male births 47XXY (most common), mosaics, 48, XXXY Nondisjunction occurs when making gametes and happens in both parents
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This note was uploaded on 08/30/2010 for the course BISC 105 taught by Professor Patriciawalsh during the Spring '10 term at University of Delaware.

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Human Heredity and Development_Walsh_Date_030910 - Types of...

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