Sickness and in Health

 Lately in Biology we have been studying genetics. We were assigned a project where we acted like a genetic counsler. I have created a pedigree of Greg and Olga's families explaining their history and diseases. I also answered questions over the family and what diseases will be passed on and who the carriers are.

 

 

 

PART 1

 

 

PART 2

Questions:

1. Do autosomal dominate disorders skip generations?  No, in an autosomal dominant disorder, only on3e parent has to pass on the abnormal gene for the child to have the disorder. This means if the child does not receice the abnormal gene, then it can't pass it on anymore.
2. Could Greg or his mother be carriers of the gene that causes myotonic dystrophy?  No, becuse they didn't receice the abnormal gene. If either of them had reveiced the abnormal gene, they would have the disorder and this is due to it being an autosomal dominant disorder. This means they can not pass this disorder into their children.
3. Is there a possibility that Greg's aunt or uncle is homozygous for the myotonic dystrophy gene?   It is not aq possibility, becuase if you look at my pedigree you will see that his aunt and uncle's parent's didn't both have the disorder. His mother was affected and his father wasn't. The normal gene was passed on by the father and the abnormal gene was passed on by the mother, which means his affected aunt and uncle must be heterozygeous.
4. Symptoms of myotonic dystrophy sometimes dont show up until after age fifty. What is the possibilty that Greg's cousin has inherited the MD gene?    Greg' cousin would have inheritated the MD gene, becuase neither of his parents were affected. If neither of them have it, it isnt possible for the disorder to be passed to their son.
5. What is the posibility that Greg and Olga's children can inherit the MD gene?   No, becuase greg does not have the disorder and it doesn't run in Olga's family. This means neither of them could pass on the disorder to their children.

PART 3

 

 

1. What are the hallmarks of an autosomal recessive trait?    In autosomol recessive traits, a person has to have both abnormal genes for them to have the disorder. If the person only has one abnormal gene, then they are carriers but they arent affected by the gene. This is the type of trait that can skip generations. The hallmarks of an autosomol recessive traits are that affected offspring have unaffected parents, and that the trait appears in siblings, not in the parents of the offspring.
2. What does consanguineous mean? Why is this concept especially important when discussing recessive genetic disorders?  Consanguineous is when mating happens between related individuals. Consanguinity increases the possibility of one parent being a carrier. The recessive trait can be passed through children until it can produce a homozygeous child in a later generation.
3. 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?     The doctor said that the trait is sex-linked and only men receive this trait. When you look at my pedigree, you will see that the only people wjo have the disorder are men.

 

 

PART 4

1. What are the characteristics of X-linked recessive inheritance?   X-linked disease is never passed directly from father to son, males are much more likely to be affected than females. If the disease affects the men in a way that they can no longer reproduce, then men are the only people affected by the disease. All males in the family that are affected are related through their mothers and the trait is usually passed from a grandfather through his daughters and hgalf of his grandson's receive it.
2. Why does a son never inherit his father's defective X chromosome?    The father doesn't pass on his x chromosome to his son, he passes on the Y chromosome to him, but the daughter can get her fathers x chromosome and be a carrier, which means she can pass it onto her son.
3. What is required for a woman to display a swex-linked recessive trait?   This would only happen if her father was affected, therefor passing on his affected x chromosome and her mother was a carrier and passed on her affected x chromosome as well.
4. Return to the pedigree drawn earlier for Greg and Olga; mark those persons who are carriers of the factor VIII deficiency gene.   

     5. 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?

Olga has a 50% chance that she carries the gene, which means a 50% chance she would pass it onto her children. If she is a carrier and passed it onto a son, then he would have Factor VIII and if she passed it onto a daughter then she would be a carrier. Also Olga has a 50% chance that she doesnt carry the disease, meaning she can't pass it on.

    6.   What is the chance that Greg carries the factor VIII gene? Can he pass the gene onto his sons? His daughters? How will each be affected?

It isn't possible for Greg to carry the factor VIII gene. Men only have x chromosomes, which means if the x chromome id affected, then they have the diseas. Due to the fact that Greg is unaffected by Factor VIII he would have received his mothers unaffected x chromosome instead of the affected one. Therefore he cannot pass on the gene to any possible children he would have.