Question

Several members of a family have a very rare form of hearing disorder. You construct the following pedigree. The most likely mode of inheritance is

a. autosomal dominant since the trait does not skip generations.
b. X-linked dominant since an affected woman can have both affected sons and affected daughters.
c. autosomal recessive, where all the unaffected individuals are heterozygous for the condition.
d. mitochondrial since affected females pass the condition on to all their children and affected males do not.
e. The mode of inheritance in the above pedigree does not fit any of the previous mentioned modes in inheritance.

Answer 1

The mode of inheritance for a genetic trait can be autosomal recessive, autosomal dominant, X-linked recessive, or mitochondrial, and each has distinguishing features such as whether carriers show symptoms, which sex is more frequently affected, and generation patterns in pedigrees. The correct option is e. The mode of inheritance in the above pedigree does not fit any of the previous mentioned modes in inheritance.

Step-by-step explanation:

When investigating the mode of inheritance for a particular trait in a pedigree, it is important to understand different patterns of genetic transmission. For autosomal recessive inheritance, all affected individuals must be homozygous recessive, meaning they have two copies of the recessive allele.

Carriers of the recessive trait, who are heterozygous, do not exhibit the condition but can pass the allele to their offspring. In contrast, in autosomal dominant inheritance, an affected individual has at least one dominant allele and the condition typically appears in every generation, as it's expressed even when only one allele is mutated.

With X-linked recessive inheritance, more males than females are typically affected, and an unaffected carrier female can have affected sons while her daughters may become carriers or remain unaffected.

The affected males have one copy of the recessive allele on their X-chromosome, received from their carrier mother. An example of an X-linked recessive disorder is color blindness. In mitochondrial inheritance, the condition is passed from mothers to all of their children, as the mitochondria in the sperm are typically not involved in fertilization. The correct option is e. The mode of inheritance in the above pedigree does not fit any of the previous mentioned modes in inheritance.