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CMBM E2 CB > Enzyme Deficiencies > Flashcards

Enzyme Deficiencies Flashcards

1
Q

What is the enzyme deficiency in PKU?

A

Phenylalanine hydroxylase (PAH)

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2
Q

What happens when someone has a PAH deficiency?

A

PKU:

Phenylalanine cannot be converted to tyrosine
Subsequent buildup of phenylalanine, which is converted to phenylpyruvic acid
PP Acid excreted in urine

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3
Q

People with PKU tend to also have a deficiency in ______, which is required to synthesize ______.

A

Tyrosine; melanin

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4
Q

What enzyme is deficient in Maple Syrup Urine disease?

A

Branched-chain ketoacid decarboxylase

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5
Q

What are the branched chain amino acids?

A

Valine
Isoleucine
Leucine

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6
Q

What happens to to those with branched chain amino acid metabolism disorders?

A

Valine, leucine, and isoleucine and unable to be carboxylated and subsequently utilized for gluconeogenesis, FA synthesis, and protein synthesis. This leads to them being excreted in urine.

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7
Q

What is the treatment for Maple Syrup Urine disease?

A

Dietary restriction of intake of the branched chain AAs

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8
Q

What is the single most common genetic condition?

A

G6P dehydrogenase deficiency

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9
Q

Which pathway is G6PD involved in?

A

The oxidative step of PPP – cannot convert G-6-P to ribose

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10
Q

What is the net result of G6PDD?

A

Reduced ability to produce NADPH

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11
Q

Which cells are particularly affected by G6PDD?

A

Red blood cells – cannot protect themselves from oxidative damage without NADPH (reducing agent)

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12
Q

Symptoms of G6PDD typically do not present until there is an oxidative assault. Three main sources for this are….

A
  1. Infection (cold, flu, etc)
  2. Drugs (NSAIDs, sulfa drugs, quinolones, etc)
  3. Foods (fava beans, legumes, menthol-containing foods)
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13
Q

Acute oxidative damage in someone with G6PDD can lead to ______.

A

Hemolytic anemia

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14
Q

What is the clinical presentation of hemolytic anemia?

A 
Paleness
Jaundice
Dark urine
Fatigue
SOB
Splenomegaly
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15
Q

G6PDD is a significant cause of _____ in newborns.

A

Jaundice

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16
Q

Why does hemolytic anemia cause jaundice?

A

Lysis of RBCs releases heme, which is typically broken down to bilirubin and excreted by the liver. An excess of RBCs overloads the liver.

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17
Q

What enzyme is deficient in classical galactosemia?

A

Galactose 1-phosphate uridyl transferase

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18
Q

What enzyme is deficient in classical galactosemia?

A

Galactokinase

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19
Q

When does galactosemia present and what does it look like?

A

First two weeks of life

Newborns present with vomiting, lethargy, failure to thrive, and jaundice

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20
Q

How is galactosemia treated?

A

Feeding infants formula lacking milk sugars (lactose and galactose)

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21
Q

What enzyme is deficient in fructose intolerance?

A

Fructose 1-phosphate aldolase (or Aldolase B)

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22
Q

What are the glycogen storage disorders affecting the liver?

A

Von Gierke disease
Cori disease
Anderson disease
Hepatic phosphorylase deficiency

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23
Q

Enzyme deficiency in Von Gierke disease

A

Glucose-6-phosphatase

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24
Q

Enzyme deficiency in Cori disease

A

Amylo-1, 6-glucosidase (debrancher enzyme)

25
Q

Enzyme deficiency in Anderson disease

A

Glycogen brancher enzyme

26
Q

Which glycogen storage disease is involved with glycogenesis?

A

Anderson disease

27
Q

Clinical presentation of Von Gierke disease

A

Hepatomegaly

Hypoglycemia

28
Q

Clinical presentation of Cori disease

A

Hepatomegaly

Muscle weakness

29
Q

Clinical presentation of Anderson disease

A

Hypotonia
Abnormal liver function within first year of life
Progresses to liver failure very quickly

30
Q

Clinical presentation of hepatic phosphorylase deficiency

A

Hepatomegaly
Hypoglycemia
Failure to thrive

31
Q

Which glycogen storage diseases affect muscle?

A

Pompe disease

McArdle disease

32
Q

Enzyme deficiency in Pompe disease

A

lysosomal enzyme alpha-1,4-glucosidase

necessary for glycogenolysis

33
Q

Enzyme deficiency in McArdle disease

A 
Muscle phosphorylase
(necessary for breakdown of muscle glycogen during exercise)
34
Q

Enzyme deficiency in CAH

A

90% of cases are due to 21-hydroxylase

35
Q

Androgen Insensitivity Syndrome is caused by

A

Defective testosterone receptors

36
Q

What is the most common autosomal dominant single-gene disorder in Western society?

A

Familial hypercholesterolemia

37
Q

Familial hypercholesterolemia leads to

A

Premature coronary artery disease

38
Q

What is the treatment for familial hypercholesterolemia?

A

Dietary restrictions and use of statins (HMG-CoA reductase inhibitors)

39
Q

Pathology of familial hypercholesterolemia

A

Problems with LDL receptor:

  1. Reduced/defective biosynthesis
  2. Reduced/defective transport
  3. Abnormal binding of LDL by the receptor
  4. Abnormal internalization of the receptor
40
Q

Problems with LDL receptors leads to…

A

Increased endogenous synthesis of cholesterol

41
Q

Two examples of mucopolysaccharidoses

A

Hunter syndrome

Sanfilippo (most common)

42
Q

Calling card of MPSs

A

Coarsening of facial features

babies look like grown men

43
Q

Tay Sachs death usually occurs because of

A

Respiratory infections

44
Q

Enzyme deficiency in Tay Sachs

A

Subunit of beta-hexosaminidase

45
Q

Calling card of Tay Sachs

A

Cherry red spot in center of macula fundus

46
Q

Most common sphingolipidoses

A

Gaucher

47
Q

Enzyme deficiency in Gaucher

A

Glucosylceramide beta-glucosidase

48
Q

Enzyme deficiency in Lesch Nyhan

A

HGPRT

49
Q

What is HGPRT involved in?

A

Salvage pathway of purine synthesis

50
Q

Lesch Nyhan patients produce more/less purines

A

More
200x higher levels

Results in excess uric acid

51
Q

How is Lesch Nyhan treated?

A

Allopurinol

52
Q

What does adenosime deaminase do in the body?

A

Responsible for conversion of AMP to IMP in the purine salvage pathway

53
Q

Why is SCID known as “bubble boy” syndrome?

A

Patients with ADA are severely deficient in both T and B cells, leaving them without a functional immune system

54
Q

Adenosine deaminase deficiency is responsible for approx. 15% of cases of….

A

Severe combined immunodeficiency syndrome (SCID)

55
Q

Potential future treatment for SCID

A

Gene therapy: inserting function adenosine deaminase gene using retroviral vectors

56
Q

Potential complication of using gene therapy for SCID

A

Patients in clinical trial developed leukemia

57
Q

What are porphyrins?

A

Ringed structures which can chelate metal ions

58
Q

Two main tissues affected by porphyrin metabolism disorders…

A

Liver – cytochromes

Erythrocytes – hemoglobin

59
Q

Enzyme deficiency in acute intermittent porphyria

A

Uroporphyrinogen I synthase

CMBM E2 CB (6 decks)

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