HumanInheritance160-page8 - As many as 1 in 20 eggs...

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Human Inheritance Patterns - 8 Autosomal Non-Disjunction Survival with an autosomal non-disjunction is rare. Autosomal Monosomy non- disjunctions result in non-viable embryos. Most trisomy autosomal non-disjunctions are also non-viable, but there are few exceptions, most commonly with chromosome 21 and sometimes 18 and 13. Trisomy G or 21 or Down syndrome About 75% of Trisomy 21 occurrences are in the egg.
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Unformatted text preview: As many as 1 in 20 eggs produced after the age of 40 may carry this chromosome abnormality. There is also some increased frequency in sperm associated with aging. Characteristics: Poor muscle tone, including the heart muscle Tongue and mouth not proportioned, affecting speech Mental retardation is sometimes present Immune system weakened...
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