1.
Which type of inheritance is characteristic of autosomal dominant disorders?
Correct Answer
C. Autosomal dominant
Explanation
Autosomal dominant disorders are characterized by inheritance patterns where a single copy of the mutated gene, inherited from one parent, is sufficient to cause the disorder. This means that individuals with an affected parent have a 50% chance of inheriting the disorder. It differs from autosomal recessive inheritance, where two copies of the mutated gene (one from each parent) are necessary for the disorder to manifest, and X-linked recessive inheritance, where the gene responsible for the disorder is located on the X chromosome.
2.
Autosomal dominant disorders are passed down from which parent?
Correct Answer
B. Either parent
Explanation
Autosomal dominant disorders can be inherited from either the mother or the father, as only one copy of the mutated gene is needed for expression of the disorder. This contrasts with disorders that exhibit sex-linked inheritance, where the gene responsible for the disorder is located on the sex chromosomes (X or Y) and may show different inheritance patterns depending on the sex of the parent and offspring.
3.
What is the likelihood of an individual inheriting an autosomal dominant disorder if one parent is affected?
Correct Answer
A. 50%
Explanation
If one parent is affected by an autosomal dominant disorder, there's a 50% chance that each offspring will inherit the mutated gene and, consequently, the disorder. This is because each parent contributes one copy of their genes to their offspring, and the inheritance of the mutated gene follows Mendelian principles of inheritance. However, it's important to note that this probability applies to each individual offspring independently and does not change based on the number of children a couple has.
4.
Which of the following is a characteristic of autosomal dominant disorders?
Correct Answer
C. Only one copy of the mutated gene is needed for expression
Explanation
Autosomal dominant disorders are characterized by the presence of a mutated gene on one of the autosomal chromosomes. This means that only one copy of the mutated gene is sufficient for an individual to express the disorder. Even if the other copy of the gene is normal, it cannot fully compensate for the effects of the mutated gene, resulting in the manifestation of the disorder.
5.
Which disorder is caused by a mutation in the BRCA1 gene?
Correct Answer
D. Hereditary breast and ovarian cancer syndrome
Explanation
Mutations in the BRCA1 gene are associated with an increased risk of developing breast and ovarian cancer. This disorder is inherited in an autosomal dominant pattern, meaning that individuals who inherit a single copy of the mutated BRCA1 gene have an increased susceptibility to developing these types of cancer. The presence of the mutated gene increases the likelihood of developing cancer, but not everyone with the mutation will necessarily develop the disease.
6.
Which autosomal dominant disorder is characterized by the presence of multiple noncancerous tumors in various parts of the body?
Correct Answer
C. Neurofibromatosis
Explanation
Neurofibromatosis is characterized by the growth of multiple noncancerous tumors on nerves throughout the body. It is inherited in an autosomal dominant pattern, meaning that individuals who inherit a single copy of the mutated gene from an affected parent have a 50% chance of developing the disorder. The severity and specific manifestations of neurofibromatosis can vary widely among affected individuals, even within the same family.
7.
What is the inheritance pattern of Marfan syndrome?
Correct Answer
A. Autosomal dominant
Explanation
Marfan syndrome is inherited in an autosomal dominant pattern, meaning that only one copy of the mutated gene is needed for an individual to express the disorder. This means that if one parent has Marfan syndrome, each child has a 50% chance of inheriting the mutated gene and developing the disorder. Marfan syndrome affects the body's connective tissue, leading to a range of physical features and potential health complications, such as elongated limbs, heart valve abnormalities, and aortic aneurysms.
8.
Which autosomal dominant disorder is characterized by progressive degeneration of nerve cells in the brain?
Correct Answer
A. Huntington's disease
Explanation
Huntington's disease is characterized by progressive degeneration of nerve cells in the brain, leading to a range of physical, cognitive, and psychiatric symptoms. It is inherited in an autosomal dominant pattern, meaning that individuals who inherit a single copy of the mutated gene from an affected parent will develop the disorder. The onset and progression of Huntington's disease can vary widely among affected individuals, but it ultimately leads to significant disability and a shortened lifespan.
9.
In autosomal dominant disorders, if an individual does not inherit the mutated gene, what is their risk of passing the disorder to their offspring?
Correct Answer
A. 0%
Explanation
If an individual does not inherit the mutated gene for an autosomal dominant disorder, they will not pass the disorder on to their offspring. This is because autosomal dominant disorders require the presence of at least one copy of the mutated gene for the disorder to manifest. If an individual does not carry the mutated gene, they cannot pass it on to their children, and their offspring will not be at risk of inheriting the disorder.
10.
Which autosomal dominant disorder is characterized by abnormalities in the connective tissue, leading to tall stature, long limbs, and other physical features?
Correct Answer
A. Marfan syndrome
Explanation
Marfan syndrome is characterized by abnormalities in the connective tissue, leading to tall stature, long limbs, and other physical features. It is inherited in an autosomal dominant pattern, meaning that only one copy of the mutated gene is needed for an individual to express the disorder. Marfan syndrome can affect multiple organ systems, including the skeletal, cardiovascular, and ocular systems, and its manifestations can vary widely among affected individuals. Early diagnosis and management are important for minimizing complications and improving quality of life for individuals with Marfan syndrome.