Chapter 05: Genetic Disorders

Chapter 05: Genetic Disorders

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

MULTIPLE CHOICE

1. Which of the following diseases is caused by a trinucleotide repeat mutation?
2. Marfan syndrome
3. Achondroplastic dwarfism
4. Fanconi syndrome
5. Fragile X syndrome
6. Hemophilia B

ANS: D, Fragile X syndrome is caused by a trinucleotide repeat mutation of the long arm of the X chromosome. Patients with the disease present with mental retardation and enlarged testes.

2. In which of the following Mendelian disorders is the age of onset delayed and the symptoms of the disease do not appear before adulthood?
3. Tay-Sachs disease
4. Niemann-Pick disease
5. Huntington disease
6. Marfan syndrome
7. Turner syndrome

ANS: C, Symptoms of Huntington disease, which include chorea and mental deterioration, are typically delayed and do not appear before adulthood.

3. Mutation of the gene for lysyl hydroxylase in the kyphoscoliosis type Ehlers-Danlos syndrome (ED type VI) causes weakness of bones and cutis laxa because of abnormal collagen
4. synthesis
5. secretion
6. cross-linking
7. degradation
8. resorption

ANS: C, Lysyl hydroxylase is an enzyme that is essential for cross-linking of collagen. Without it, the collagen never achieves full structural integrity and strength; accordingly, the bones are weak and prone to deformation, whereas the skin becomes hyperextensible (“cutis laxa”).

4. Splenomegaly and skeletal changes due to a nonlethal lysosomal storage disease caused by the mutation of the gene encoding glucocerebrosidase are features of which disease?
5. Tay-Sachs disease
6. Niemann-Pick disease
7. Hurler disease
8. Gaucher disease
9. Hunter syndrome

ANS: D, Gaucher disease is caused by a mutation of the gene encoding glucocerebrosidase. In the most common of the three forms of Gaucher disease, which accounts for 99% of all cases, there is splenomegaly, lymphadenopathy, involvement of the bone marrow, and skeletal changes.