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Fanconi Anemia Is An Inherited Anemia That Leads To Bone Marrow Failure ( Aplastic Anemia).?

Leukemia and blood cancer discussion.

Fanconi Anemia Is An Inherited Anemia That Leads To Bone Marrow Failure ( Aplastic Anemia).?

Postby Marmion » Wed Sep 20, 2017 11:33 pm

It is an autosomal recessive disorder. It occurs equally in males and females, and found in all ethnic groups; it can affect all systems of the body, and many patients eventually develop acute myelogenous leukemia at an early age; they also develop a variety of other head, neck, gynecological and or gastrointestinal cancers; the patient can be cured of the FA blood problem by having a successful bone marrow transplant, but must still have regular examinations to watch for signs of cancer. A couple (both with FA) who have already had one child with FA decide that they would like to have another child.

a.) What was the genotype of the child with FA?

b.) What is the probability that their next child will have FA?
Marmion
 
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Fanconi Anemia Is An Inherited Anemia That Leads To Bone Marrow Failure ( Aplastic Anemia).?

Postby Lev » Wed Sep 20, 2017 11:39 pm

Explanation follows... but first here are the answers.

a) aa (as opposed to AA or Aa)

b) 100%

We need to give the gene that controls the trait a symbol.
Let's call it the anemia gene, and lets make the symbol, "A" or "a" depending on whether we are working with the "normal" non-Fanconi anemia allele or the diseased, Fanconi anemia allele, respectively.

It is autosomal recessive, which means we can ascribe a lower-cased symbol to the recessive allele of the gene and a capital letter for the dominant allele of the gene.
The autosomal part means that we don't have to worry about connecting the alleles to an X or Y chromsome.

The exhibition of a recessive trait requires that 2 copies of the recessive allele be present (remember dominant traits only require one copy of the dominant allele... the other allele can be the dominant or recessive).

So, the recessive disorder requires that an individual afflicted with the disease possess 2 copies of the recessive allele, in our case, a.

So, anyone with the disorder must be aa.


For the next child, both parents have FA, so both have the genotype aa.
aa x aa = 100% aa

Here is a Punnett Square...

Mom's alleles on the top and dad's alleles on the side.
Offspring allele possibilities in the middle.

.....a...a

a..aa..aa

a..aa..aa
Lev
 
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Joined: Mon Jan 20, 2014 12:34 am


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