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Kaplan Qbank USMLE



Author5 Posts
  #1

About autosomal dominant inheritance all are true except

A) It is always expressed in homozygotes
B) Always one parent is affected
C) 50% of children affected
D) Offspring of a nondiseased child of a diseased parent will not have the mutant gene.


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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."

  #2

shockedshocked

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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."

  #3

raised eyebrowraised eyebrow

___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."

  #4

a smiling face

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"chhak de phhatte"

  #5

KG u nailed it ..........nod

A single, abnormal gene on one of the autosomal chromosomes (one of the first 22 "non-sex" chromosomes) from either parent can cause certain diseases. One of the parents will usually have the disease (since it is dominant) in this mode of inheritance. Only one parent must have an abnormal gene in order for the child to inherit the disease.

For an autosomal dominant disorder: If one parent has an abnormal gene and the other parent a normal gene, there is a 50% chance each child will inherit the abnormal gene, and therefore the dominant trait.

In other words, if it is assumed that 4 children are produced from a couple in which one parent has an abnormal gene for a dominant disease, the STATISTICAL expectation is for:
2 children normal
2 children with the disease
This does not mean that children WILL necessarily be affected. It does mean that EACH child has a 50:50 chance of inheriting the disorder. Children who do not inherit the abnormal gene will not develop or pass on the disease.



___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."







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