Enzyme And Collagen Disorders

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Question 1

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Multiple Choice

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

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Metabolism during prenatal life is too slow to require full enzyme activity.

The deficient enzyme's activity was performed by maternal enzymes before birth.

During the fetal phase of life, the newborn was not exposed to the protein that the enzyme is responsible for degrading.

Although the newborn cannot synthesize the enzyme after birth, the initially stored enzyme performs its functions until the level is fully depleted.

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Question 2

Free

Multiple Choice

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

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Increased intake of phenylalanine; decreased intake of tyrosine

Increased intake of phenylalanine; increased intake of tyrosine

Decreased intake of phenylalanine; decreased intake of tyrosine

Decreased intake of phenylalanine; increased intake of tyrosine

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Question 3

Free

Multiple Choice

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

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Ashkenazi Jews

French Canadians from the Quebec area

Celts from Ireland and Scotland

Africans from equatorial areas

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Question 4

Free

Multiple Choice

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

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Increased skin pigmentation

Excessive urination

Fragile bones

Small stature

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Question 5

Free

Multiple Choice

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

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Hopping on one foot

Learning the names of animals

Deciding what to give as a present

Counting the number of objects in a picture

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Question 6

Multiple Choice

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

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Most births are post-mature.

There is a high incidence of infertility.

The infant develops PKU.

There is a high incidence of cardiovascular birth defects.

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Question 7

Multiple Choice

Which statement regarding lysosomal storage diseases is true?

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A gene defect makes lysosomes unable to store degraded compounds.

Accumulation of stored iron results in cell, tissue, and organ dysfunction.

Defective enzymes result in the accumulation of potentially toxic substances.

Mutations in the genes coding for different types of collagen produce substances that are toxic to brain cells.

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Question 8

Multiple Choice

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?

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All sons will be unaffected; all daughters will be carriers.

All sons will be carriers; all daughters will be affected.

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.

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.

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Question 9

Multiple Choice

Which ethnic group has the highest incidence of Gaucher disease?

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Ashkenazi Jews

Asian Americans

American Indians

Individuals of Mediterranean descent

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Question 10

Multiple Choice

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

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Enzyme therapy can reduce complications for some patients.

When proper dietary management is instituted early, complications can be prevented.

Insulin therapy can result in prevention of the development of type 2 diabetes mellitus.

Prophylactic therapy with antibiotics can prevent early death from pneumonia and other infections.

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Question 11

Multiple Choice

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

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The enzyme increases the destruction of glucosamine-filled macrophages.

The drug acts as a cofactor, increasing the activity of the mutated enzyme.

The drug increases production of all blood cells in the bone marrow, including white blood cells, which have not stored glucosylceramide.

The enzyme is absorbed through the plasma membranes of affected cells and converts the stored glucosylceramide into its constituent molecules.

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Question 12

Multiple Choice

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

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Enlarged, palpable liver

Weight in the 95th percentile

Does not yet say "mama" or "dada"

Skin tone appears slightly lighter than that of either parent

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Question 13

Multiple Choice

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

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Daily ingestion of oral sapropterin hydrochloride (Kuvan)

Intravenous enzyme replacement with alpha-L iduronidase

Weekly phlebotomy with removal of excess red blood cells

Intravenous enzyme replacement with imiglucerase (Cerezyme)

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Question 14

Multiple Choice

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

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Hurler syndrome

Hunter syndrome

Gaucher type 2

Tay-Sachs disease

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Question 15

Multiple Choice

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

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Hurler syndrome is an autosomal-dominant disorder, and Hunter syndrome is autosomal recessive.

Hunter syndrome is an autosomal-dominant disorder, and Hurler syndrome is autosomal recessive.

Individuals with Hurler syndrome become cognitively impaired in early childhood, whereas those with Hunter syndrome often retain intellectual ability until later in life.

Individuals with Hunter syndrome become cognitively impaired in early childhood, whereas those with Hurler syndrome often retain intellectual ability until later in life.

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Question 16

Multiple Choice

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

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The excess mucopolysaccharides accumulate inside the lysosomes within the liver cells.

The excess mucopolysaccharides accumulate inside the cells of the liver and the spleen.

The excess glycosaminoglycans weaken the muscles of the abdomen, and all contents move forward.

The excess glycosaminoglycans cause the person to develop type 2 diabetes, with greatly increased abdominal fat.

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Question 17

Multiple Choice

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?

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Skewed X inactivation allowed more paternal X expression for Lucy and more maternal X expression for Lester.

Lucy's mother had better prenatal care, including good diet, exercise, and vitamins, than Lester's mother.

It is likely that Lucy has been misdiagnosed and really has MPS2.

The disorder has wide variability in expression of severity.

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Question 18

Multiple Choice

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

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All sons will be unaffected; all daughters will be carriers.

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

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

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.

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Question 19

Multiple Choice

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?

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The girl must have a different father than her brother.

The daughter is seeking the same attention that is given to her brother.

The inactivation of one X chromosome in female cells is a totally random event.

In addition to inheriting one affected allele, the daughter has developed a somatic mutation.

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Question 20

Multiple Choice

What is the pathologic basis of Fabry disease?

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Increased degradation of globotriaosylceramide

Increased accumulation of globotriaosylceramide

Deficiency in the number of liver lysosomes

Excessive number of liver lysosomes

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