Question

Assume that a recessive allele (f) is associated with a severe language disorder. An unaffected male wants to determine the genotypes of his wife, his parents, and himself. His mother has the language disorder. Neither he nor his wife has the language disorder, but one of their five children does. What is the genotype for each individual? Answers may be used more than once or not at all. (Note: the gene associated with this language disorder is on an autosome.)

Answer 1

Answer: The autosomal dominance inheritance pattern occurs when the altered allele is dominant over the normal one and only one copy is sufficient for the disease to be expressed. Being autosomal, the gene is found in one of 22 pairs of non-sex chromosomes, or autosomes, and can affect sons and daughters equally. The altered allele may have been inherited from both the father and the mother. It usually oocurs in all generations of a family. Each affected person normally has an affected parent and a 50% chance with each child that he inherits the mutated allele and develops the autosomal dominant disease.

Answer 2

Answer:

MOM: ff  UNAFFECTED MALE: Ff  WIFE: Ff    CHILDREN: #1 ff, #2 FF, #3 Ff, #4 FF, #5 Ff

Explanation:

We know that a recessive allele (f) is associated with the language disorder. This means that to have the severe language disorder, one must have ff for the gene to be expressed. A member cannot have the disorder if FF OR Ff is displayed. Remember that (F) is a dominant allele, meaning that if it is displayed (even once in the genotype!), the recessive allele (f) is not expressed.

Let's do a run down of the genotype in each family member.

• The male's Mother (TRUE-has disorder): [ff]

• The male (FALSE-doesn't have disorder) [Ff]
• The male's Wife (False- doesn't have it) [Ff]
• Children:  FF Ff Ff ff FF
• (there are different possibilities for each child, but remember to include ff for one child. The other four can be FF and/or ff. I think your instructor is asking you to put down all combination for their children, so you may want to do that!)

If we create a Punnett Square, we can see that combining the Man's and Wife's alleles will create a 50% chance that their offspring will have the severe language disorder or ff. It will also create a 25% chance that their offspring will not have the disorder or Ff, and another 25% chance of FF (doesn't have disorder).