Deck 10: Enzyme and Collagen Disorders

Question 1

If a man with Fabry disease has children with a woman who is a carrier for the disorder, what is the expected risk pattern?

A)All sons will be unaffected; all daughters will be carriers.
B)Sons have a 50% risk for being affected; all daughters will either be affected or carriers.
C)Daughters have a 50% risk for being affected; all sons will either be affected or carriers.
D)Each child of either gender has a 50% risk of being a carrier, a 25% risk of having the disease, and a 25% risk of neither being a carrier nor having the disease.

Answer 1

Sons have a 50% risk for being affected; all daughters will either be affected or carriers.

Question 2

Which assessment finding in a 6-month-old child suggests a possible lysosomal storage disease?

A)Enlarged, palpable liver
B)Weight in the 95th percentile
C)Does not yet say "mama" or "dada"
D)Skin tone appears slightly lighter than that of either parent

Answer 2

Enlarged, palpable liver

Question 3

Which statement regarding lysosomal storage diseases is true?

A)A gene defect makes lysosomes unable to store degraded compounds.
B)Accumulation of stored iron results in cell, tissue, and organ dysfunction.
C)Defective enzymes result in the accumulation of potentially toxic substances.
D)Mutations in the genes coding for different types of collagen produce substances that are toxic to brain cells.

Answer 3

Defective enzymes result in the accumulation of potentially toxic substances.

Question 4

What is the pathologic basis of Fabry disease?

A)Increased degradation of globotriaosylceramide
B)Increased accumulation of globotriaosylceramide
C)Deficiency in the number of liver lysosomes
D)Excessive number of liver lysosomes

Question 5

If a man with Gaucher type 1 has children with a woman who is a carrier for the disorder, what is the expected risk pattern?

A)All sons will be unaffected; all daughters will be carriers.
B)All sons will be carriers; all daughters will be affected.
C)All children will have one mutated allele and will at least be carriers; each child of either gender has a 50% risk of having the disease.
D)Each child of either gender has a 50% risk of being a carrier, a 25% risk of having the disease, and a 25% risk of neither being a carrier nor having the disease.

Question 6

Why does a person with Hurler syndrome have an enlarged abdomen?

A)The excess mucopolysaccharides accumulate inside the lysosomes within the liver cells.
B)The excess mucopolysaccharides accumulate inside the cells of the liver and the spleen.
C)The excess glycosaminoglycans weaken the muscles of the abdomen, and all contents move forward.
D)The excess glycosaminoglycans cause the person to develop type 2 diabetes, with greatly increased abdominal fat.

Question 7

Why is it important to diagnose Gaucher type 1 disease as soon as possible after birth?

A)Enzyme therapy can reduce complications for some patients.
B)When proper dietary management is instituted early, complications can be prevented.
C)Insulin therapy can result in prevention of the development of type 2 diabetes mellitus.
D)Prophylactic therapy with antibiotics can prevent early death from pneumonia and other infections.

Question 8

Which therapeutic option has been found beneficial for patients with Gaucher type 1 disease?

A)Daily ingestion of oral sapropterin hydrochloride (Kuvan)
B)Intravenous enzyme replacement with alpha-L iduronidase
C)Weekly phlebotomy with removal of excess red blood cells
D)Intravenous enzyme replacement with imiglucerase (Cerezyme)

Question 9

Why does a newborn with a genetic enzyme deficiency have a normal phenotype at birth?

A)Metabolism during prenatal life is too slow to require full enzyme activity.
B)The deficient enzyme's activity was performed by maternal enzymes before birth.
C)During the fetal phase of life, the newborn was not exposed to the protein that the enzyme is responsible for degrading.
D)Although the newborn cannot synthesize the enzyme after birth, the initially stored enzyme performs its functions until the level is fully depleted.

Question 10

What is the expected outcome of pregnancy for women with phenylketonuria (PKU) when the blood levels of phenylalanine are high throughout the pregnancy?

A)Most births are post-mature.
B)There is a high incidence of infertility.
C)The infant develops PKU.
D)There is a high incidence of cardiovascular birth defects.

Question 11

Which ethnic group has the highest incidence of Gaucher disease?

A)Ashkenazi Jews
B)Asian Americans
C)American Indians
D)Individuals of Mediterranean descent

Question 12

Which ethnic group has the highest incidence of a mutation in the PAH gene?

A)Ashkenazi Jews
B)French Canadians from the Quebec area
C)Celts from Ireland and Scotland
D)Africans from equatorial areas

Question 13

A woman who is a carrier for Fabry disease has children with a man who does not have the disorder. Their son has the disease, and their daughter also has somesymptomsof Fabry disease even though she could only have inherited one affected allele. What is the explanation for the daughter having some symptoms of Fabry disease?

A)The girl must have a different father than her brother.
B)The daughter is seeking the same attention that is given to her brother.
C)The inactivation of one X chromosome in female cells is a totally random event.
D)In addition to inheriting one affected allele, the daughter has developed a somatic mutation.

Question 14

For which disorder is the drug idursulfase (Elaprase) appropriate for enzyme-replacement therapy?

A)Hurler syndrome
B)Hunter syndrome
C)Gaucher type 2
D)Tay-Sachs disease

Question 15

How does intravenous enzyme-replacement therapy for Gaucher disease reduce the organ storage of glucosylceramide?

A)The enzyme increases the destruction of glucosamine-filled macrophages.
B)The drug acts as a cofactor, increasing the activity of the mutated enzyme.
C)The drug increases production of all blood cells in the bone marrow, including white blood cells, which have not stored glucosylceramide.
D)The enzyme is absorbed through the plasma membranes of affected cells and converts the stored glucosylceramide into its constituent molecules.

Question 16

Which action or behavior is considered an "executive function"?

A)Hopping on one foot
B)Learning the names of animals
C)Deciding what to give as a present
D)Counting the number of objects in a picture

Question 17

A pair of unrelated 4-year-olds (Lester and Lucy) have mucopolysaccharidosis 1 (MPS1). Lester has severe dysmorphic features and many skeletal anomalies. Lucyhas onlymildly coarse features and slight developmental delay. What is the best explanation for these differences?

A)Skewed X inactivation allowed more paternal X expression for Lucy and more maternal X expression for Lester.
B)Lucy's mother had better prenatal care, including good diet, exercise, and vitamins, than Lester's mother.
C)It is likely that Lucy has been misdiagnosed and really has MPS2.
D)The disorder has wide variability in expression of severity.

Question 18

How are the two mucopolysaccharide disorders Hurler syndrome and Hunter syndrome different?

A)Hurler syndrome is an autosomal-dominant disorder, and Hunter syndrome is autosomal recessive.
B)Hunter syndrome is an autosomal-dominant disorder, and Hurler syndrome is autosomal recessive.
C)Individuals with Hurler syndrome become cognitively impaired in early childhood, whereas those with Hunter syndrome often retain intellectual ability until later in life.
D)Individuals with Hunter syndrome become cognitively impaired in early childhood, whereas those with Hurler syndrome often retain intellectual ability until later in life.

Question 19

Which dietary alterations are necessary to help reduce the complications of phenylketonuria (PKU)?

A)Increased intake of phenylalanine; decreased intake of tyrosine
B)Increased intake of phenylalanine; increased intake of tyrosine
C)Decreased intake of phenylalanine; decreased intake of tyrosine
D)Decreased intake of phenylalanine; increased intake of tyrosine

Question 20

Which manifestation is a characteristic feature of untreated phenylketonuria (PKU)?

A)Increased skin pigmentation
B)Excessive urination
C)Fragile bones
D)Small stature

Question 21

A 12-year-old boy with Marfan syndrome complains to his nurse-practitioner, "My mother won't let me play football or do anything else. Isn't there something Ican do besides sitting and playing video games?" Which of the following activities may be considered less risky for this child to perform? Select all that apply.

A) Soccer (not the goalie position)
B) Riding his bike with his friends
C) Playing table tennis
D) Competitive swimming
E) Archery
F) Recreational ice-skating
G) Hiking low- to moderate-difficulty trails
H) Basketball

Question 22

Which health problem could be expected as a result of a gene mutation that affects the correct production and function of type 1 collagen?

A)Failure of blood to clot after minor trauma
B)Increased incidence of arterial and venous aneurysms
C)Increased incidence of hearing loss among children and adults
D)Restrictive lung disease from excessive stiffening of alveolar walls

Question 23

A son with osteogenesis imperfecta is born to parents with no family history of the disease. What is the most likely explanation for the son's disorder?

A)The son is not biologically related to the mother.
B)The son is not biologically related to the father.
C)The gamete of one parent had a spontaneous mutation.
D)The son's DNA underwent a spontaneous mutation during the second trimester of pregnancy.

Question 24

Couples from which ethnic group would derive the greatest benefit from genetic testing for Tay-Sachs disease?

A)Ashkenazi Jews
B)Asian Americans
C)French Canadians from Quebec
D)Individuals of Mediterranean descent

Question 25

Which clinical manifestation in a 6-month-old infant is most diagnostic for Tay-Sachs disease?

A)Anemia and bruising
B)Enlarged liver and spleen
C)Cherry red spot on the retina
D)Progressive cognitive impairment

Question 26

Which manifestation is most common among individuals with osteogenesis imperfecta type I?

A)Short stature
B)Premature birth
C)Skull deformities
D)Blue-tinged sclerae

Question 27

What is the most common cause of death among individuals with vascular Ehlers-Danlos (Ehlers-Danlos type IV)?

A)Respiratory impairment from kyphosis
B)Skin cancer (melanoma)
C)Intestinal rupture
D)Liver failure

Question 28

The mother of a teenager recently diagnosed with osteogenesis imperfecta type I (OI) asks if the problem is related to the fact that she adhered to a vegetarian diet during pregnancy. What is the most appropriate response?

A)Your diet is not related to this disease because it is an inherited disorder.
B)Although this problem can be inherited, low calcium levels are a major cause.
C)That is one possibility, especially because collagen requires proteins to form.
D)More likely, it is related to the fact that you were older than 35 years of age when you became pregnant.

Question 29

Which manifestation in a teenage boy whose mother is a carrier for Fabry disease suggests the boy may have the disorder?

A)Hearing is hyperacute.
B)Opacity is present in both eyes.
C)Fasting blood glucose level is elevated.
D)Growth spurt results in a height 6 inches taller than his siblings.

Question 30

Which substance fails to form normally in individuals with Marfan syndrome?

A)Elastin
B)Glycogen
C)Collagen
D)Fibrillin