Greg and Olga

One thing you mayyy not know about me is that I’m a genetic counselor. 😏 Justtt kiddinggg.  But, for the purpose of this lab, I did take the place of a genetics counselor for Greg and Olga.  Lovely couple.  These two (fictional) people came to me through an assignment in Schoology.  They were trying to have a baby!  But, it’s the 21st century and the element of surprise isn’t allowed anymore, the couple wanted to know the risks the child would have in being born.  Specifically, for Hemophilia and Mytonic Dystrophy.  My job was to analyze the letter they “sent” me and make pedigrees to diagram the risk of the two diseases based on the families history.  Below is the pedigrees of Greg and Olga:

Part 2

Greg and Olga had questions about the possibilities of these diseases happening to their children.

. Do autosomal dominant disorders skip generations?

No, because they are dominant and will always take over the genes unless two recessive genes are put together.

. Could Greg or his mother be carriers of the gene that causes myotonic dystrophy?

Greg’s mother and Greg could not be carriers because the grandfather is completely normal.  Unless, the grandfather was a carrier, then the mom could also be a carrier but Greg wouldn’t be a carrier.

. Is there a possibility that Greg’s aunt or uncle is homozygous for the myotonic dystrophy () gene?

The grandfather would have to be a carrier, which he might be because it’s unknown, for the aunt and uncle to be homozygous.  Since the aunt had a son without the disease though, it is unlikely she is homozygous.

. Symptoms of myotonic dystrophy sometimes don’t show up until after age fifty. What is the possibility that Greg’s cousin has inherited the  gene?

There is a high chance that Greg’s cousin inherits the disease since Greg’s aunt is affected by the disease.

. What is the possibility that Greg and Olga’s children could inherit the  gene?

It is highly unlikely that Greg and Olga’s child inherits Mytonic Dystrophy.  There is no sign of Mytonic Dystrophy on Olga’s side of the family and it is highly unlikely that Greg has the disease.

Part 3

. What are the hallmarks of an autosomal recessive trait?

Hallmarks of an autosomal recessive trait is the trait skipping generations and affecting both male and females.  The autosomal describes the unisex affects.  The trait skipping describes the recessive trait.

. What does consanguineous mean? Why is this concept especially important when discussing recessive genetic disorders?

Consanguineous means relating to or detonating people descended from the same ancestor.  This concept is especially important when discussing recessive gene disorders because there is a possibility that the gene shows up in you or your child since it is passed down recessively through your ancestors.

. What is it about the inheritance pattern of factor  deficiency seen in Greg and Olga’s pedigree that point toward it not being an autosomal recessive trait?

The factor deficiency only affects boys which would point to the trait being sex-linked.

Part 5

. What are the characteristics of X-linked recessive inheritance?

The characteristics of an X-linked recessive is the disease only affecting boys and not every generation.  Also, the mother had to pass on a recessive defective gene.

. Why does a son never inherit his father’s defective X chromosome?

A son never inherits his fathers defective X chromosome because if a boy is being born, the father had passed on a Y chromosome and not an X chromosome.

. What is required for a woman to display a sex-linked recessive trait?

It is required that both X chromosomes are defective genes.  This means that the father would have had to have the recessive gene and the mother needed to also have the recessive gene.

. What is the chance that Olga carries the gene for factor  deficiency? Calculate the probability that she will pass it to her offspring. Will male children be affected in a different way than female children?

There is a 50% chance that Olga carries the gene for factor deficiency based on a Punnett square I wrote on a random piece of paper.  For females, it’s harder to get the gene.  Both parents have to be carriers to have the gene passed on.  For males, due to the fact they only have one X chromosome, only the mother needs to pass on the gene.  Where there is a gap on the Y chromosome, the X chromosome fills the gap and takes over, becoming dominant.

. What is the chance that Greg carries the factor  gene? Can he pass the gene on to his sons? His daughters? How will each be affected?

There is a zero percent chance that Greg carries the gene otherwise he would currently be affected since factor deficiency is only on the X chromosome. There is a zero percent chance that Greg personally passes on the disease to his son or daughter.  But, his son could still be affected if Olga carries and passes on the gene.

That was all the work we did with Greg and Olga.  Now, I had to do some experimenting for myself and my family.  We had this weird test strip thingys that Mr. Ludwig provided.  These strips had a certain taste to them.  But, not everyone could taste it.  If you had a certain protein, you could taste the strip and the opposite if not.  I (unfortunately) could taste it.  Afterwards, we had to take the strips and test our family members to see if the trait was autosomal dominant, autosomal recessive, or sex-linked.  To visually observe it, based on our family data, we made a pedigree.

Based on the rest of the class pedigrees, we could determine that this protein is autosomal dominant.