Tuesday, March 6, 2012

In Sickness and In Health




Part II
Questions
Do autosomal dominant disorders skip generation
No, you either have it or you don't. If its dominant you have a chance of passing it down.

Could Greg or his mother be carriers of the gene that causes myotonic dystrophy?
No they could not because muscular dystrophy is a dominant gene.

Is there a possibility that Greg’s aunt or uncle is homozygous for the myotonic dystrophy (MD) gene?
Yes because the two both have the gene for the disease. 

Symptoms of myotonic dystrophy sometimes don’t show up until after age fifty. What is the possibility that Greg’s cousin has inherited the MD gene?
 His cousin has a 50% chance of having the MD gene because you either have the gene or you don't.

What is the possibility that Greg and Olga’s children could inherit the MD gene?
There is a 0% possibility that Greg and Olga's children would inherit the MD gene because the parents don't have the gene and as stated the MD gene is dominant. If they don't have it they can't pass it on. 

Part III
What are the hallmarks of an autosomal recessive trait?
Autosomal recessive traits skip generations and happen in both males and females.

What does consanguineous mean? Why is this concept especially important when discussing recessive genetic disorders?
Consanguineous means the relation to the same past ancestor. It is important be recessive traits skip generations. Knowing would help determine whether you may inherit the disease or not due to the relation of your ancestor.

What is it about the inheritance pattern of factor VIII deficiency seen in Greg and Olga’s pedigree that point toward it not being an autosomal recessive trait?
Its only happened between 2 people within two different generations. The one before greg in Olgas family and Gregs brother in the next generation. But they are not related. And it is a sex-linked disease. So far it has only happened in men.

Part IV
What are the characteristics of X-linked recessive inheritance?
They could have it because it has happened in both sides with the brothers and if they have a boy it is possible.

Why does a son never inherit his father’s defective X chromosome?
He never inherits it from his father because he gets the x chromosome from his mother.


What is required for a woman to display a sex-linked recessive trait?
If she has a dominant trait and a recessive allele, her phenotype will not show that trait.


Return to the pedigree drawn earlier for Greg and Olga; mark those persons who are carriers of the factor VIII deficiency gene
Olga's nephews and cousins are carriers of the factor VIII deficiency gene because their father carries the trait within his genes. 


What is the chance that Olga carries the gene for factor VIII deficiency? Calculate the probability that she will pass it to her offspring. Will male children be affected in a different way than female children?
I'd say she has a low chance of carrying the gene because it seems that mostly men carry the gene meaning they'd be the one to pass it on to the men after them. 


What is the chance that Greg carries the factor VIII gene? Can he pass the gene on to his sons? His daughters? How will each be affected?
Greg has a chance of carrying the factor VIII gene only because his brother has it as well; and he could pass the gene down to male children. But because he has it, the chances are slimmer. Boys may be infected with the full gene while girls may be the carrier. 


Meiosis and Genetics (: