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CMBM E2 CB > Enzyme Deficiencies > Flashcards

Enzyme Deficiencies Flashcards

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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

Study These Flashcards
A

Amylo-1, 6-glucosidase (debrancher enzyme)

25
Enzyme deficiency in Anderson disease
Glycogen brancher enzyme
26
Which glycogen storage disease is involved with glycogenesis?
Anderson disease
27
Clinical presentation of Von Gierke disease
Hepatomegaly | Hypoglycemia
28
Clinical presentation of Cori disease
Hepatomegaly | Muscle weakness
29
Clinical presentation of Anderson disease
Hypotonia Abnormal liver function within first year of life Progresses to liver failure very quickly
30
Clinical presentation of hepatic phosphorylase deficiency
Hepatomegaly Hypoglycemia Failure to thrive
31
Which glycogen storage diseases affect muscle?
Pompe disease | McArdle disease
32
Enzyme deficiency in Pompe disease
lysosomal enzyme alpha-1,4-glucosidase | necessary for glycogenolysis
33
Enzyme deficiency in McArdle disease
``` Muscle phosphorylase (necessary for breakdown of muscle glycogen during exercise) ```
34
Enzyme deficiency in CAH
90% of cases are due to 21-hydroxylase
35
Androgen Insensitivity Syndrome is caused by
Defective testosterone receptors
36
What is the most common autosomal dominant single-gene disorder in Western society?
Familial hypercholesterolemia
37
Familial hypercholesterolemia leads to
Premature coronary artery disease
38
What is the treatment for familial hypercholesterolemia?
Dietary restrictions and use of statins (HMG-CoA reductase inhibitors)
39
Pathology of familial hypercholesterolemia
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
Problems with LDL receptors leads to...
Increased endogenous synthesis of cholesterol
41
Two examples of mucopolysaccharidoses
Hunter syndrome | Sanfilippo (most common)
42
Calling card of MPSs
Coarsening of facial features | babies look like grown men
43
Tay Sachs death usually occurs because of
Respiratory infections
44
Enzyme deficiency in Tay Sachs
Subunit of beta-hexosaminidase
45
Calling card of Tay Sachs
Cherry red spot in center of macula fundus
46
Most common sphingolipidoses
Gaucher
47
Enzyme deficiency in Gaucher
Glucosylceramide beta-glucosidase
48
Enzyme deficiency in Lesch Nyhan
HGPRT
49
What is HGPRT involved in?
Salvage pathway of purine synthesis
50
Lesch Nyhan patients produce more/less purines
More 200x higher levels Results in excess uric acid
51
How is Lesch Nyhan treated?
Allopurinol
52
What does adenosime deaminase do in the body?
Responsible for conversion of AMP to IMP in the purine salvage pathway
53
Why is SCID known as "bubble boy" syndrome?
Patients with ADA are severely deficient in both T and B cells, leaving them without a functional immune system
54
Adenosine deaminase deficiency is responsible for approx. 15% of cases of....
Severe combined immunodeficiency syndrome (SCID)
55
Potential future treatment for SCID
Gene therapy: inserting function adenosine deaminase gene using retroviral vectors
56
Potential complication of using gene therapy for SCID
Patients in clinical trial developed leukemia
57
What are porphyrins?
Ringed structures which can chelate metal ions
58
Two main tissues affected by porphyrin metabolism disorders...
Liver -- cytochromes | Erythrocytes -- hemoglobin
59
Enzyme deficiency in acute intermittent porphyria
Uroporphyrinogen I synthase

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