Robbins & Cotran Pathologic Basis of Disease 9th Edition by Vinay Kumar

Robbins & Cotran Pathologic Basis of Disease 9th Edition by Vinay Kumar

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Kumar: Robbins and Cotran Pathologic Basis of Disease, 9th Edition

Chapter 05: Genetic Disorders

Test Bank

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.

5. A 7-year-old child complained of frequent muscle cramps during play. A muscle biopsy revealed accumulation of glycogen in the skeletal muscle cells and a lack of muscle phosphorylase. Which form of glycogenosis is this?
6. Type I (von Gierke disease)
7. Type II (Pompe disease)
8. Type III (Cori-Forbes’ disease)
9. Type IV (Andersen disease)
10. Type V (McArdle disease)

ANS: E, Type V glycogenosis, also known as McArdle disease, is caused by muscle phosphorylase deficiency. Patients present with muscle cramps. In these patients, the blood level of lactic acid does not rise after exercise, because the enzyme deficiency prevents anaerobic glycolysis in the muscle cells.

6. Which malignancy occurs at a high rate in persons affected with Down syndrome?
7. Acute lymphoblastic leukemia
8. Chronic lymphocytic leukemia
9. Chronic myelogenous leukemia
10. Plasmacytoma
11. Brain tumors

ANS: A, Children with Down syndrome are at a 10 to 20-fold higher risk of developing acute lymphoblastic leukemia or acute myelogenous leukemia than are their age-matched controls.

7. Chromosome 22q11 deletion is typically associated with
8. rocker-bottom feet
9. horseshoe kidneys
10. thymic hypoplasia
11. microphthalmia
12. simian crease on hands

ANS: C, Chromosome 22q11 deletion is found in children who have DiGeorge syndrome and velocardiofacial syndrome. These two syndromes are known to be closely related  and are known as the CATCH 22 syndrome (cardiac abnormalities, anomalous facial features, thymic hypoplasia with T-cell deficiencies, cleft palate, and hypocalcemia due to hypoparathyroidism resulting from chromosome 22q11 deletion).

8. An infertile woman was examined cytogenetically and was found to have deletions of portions of the long arm and short arm of the chromosome X, resulting in a ring chromosome, 46,X,r(X). Which of the following is the most likely diagnosis?
9. Gonadal dysgenesis
10. Hermaphroditism
11. Male pseudohermaphroditism
12. Female pseudohermaphroditism
13. Turner syndrome

ANS: E, A ring chromosome, 46,X,r(X), is found in patients with Turner syndrome. Such patients are in a minority, since most patients with Turner syndrome (57%) actually have a 45,X karyotype and lack one of the two X chromosomes.