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CMBM exam 3 > Enzyme Deficiencies > Flashcards

Enzyme Deficiencies Flashcards

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0
Q

Most IEMs, genetics wise are …

A

autosomal recessive or X linked recessive

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1
Q

groups of inborn errors of metabolism

A
  1. metabolites
  2. metabolic pathway
  3. Function of enzyme
  4. function of organelle
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2
Q

IEMs of amino acid metabolism

A

PKU
Oculocutaneous albinism
branched chain aa metabolism - maple syrup urine disease

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3
Q

IEMs of Carbohydrate metabolism

A

G6PDD
monosaccharide metabolism - galactosemia, hereditary fructose intolerance
glycogen storage disorders - von gierke, cori, anderson, pompe, Mcardle syndromes; hepatic phosphorylase deficiency

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4
Q

IEMs of steroid metabolism

A

congenital adrenal hyperplasia

androgen insensitivity syndrome

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5
Q

IEM of Lipid metabolism

A

familial hypercholesterolemia

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6
Q

Lysosomal storage disorders

A

mucopolysaccharidoses

sphingolipidoses

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7
Q

Purine/pyrimidine metabolism

A

Lesch Nyhan syndrome

SCID

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8
Q

IEM of Porphyrin metabolism

A

Hepatic

Erythropoietic

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10
Q

Untreated PKU (phenylketonuria) leads to

A

severe intellectual impairments and development of seizures

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10
Q

Defects in branched chain AA metabolism leads to

A

Maple syrup urine disease

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11
Q

What deficiency causes PKU?

A

defect in the enzyme Phenylalanine hydroxylase (PAH) which converts Phenylalanine into Tyrosine, results in deficiency of Tyrosine which is required for melanin synthesis
this leads to buildup of phenylalanine which then converts to phenylpyruvic acid that is excreted through urine

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12
Q

Branched chain AA?

A

Valine
Leucine
Isoleucine

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13
Q

What is the prognosis for pts with Maple syrup disease?

A

tend to be susceptible to deterioration even with dietary restriction
tend to suffer recurrent illnesses from the catabolic protein breakdown

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14
Q

What defect leads to Maple syrup disease?

A

branched chain ketoacid decarboxylase deficiency leads to Val, Leu and Ile

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15
Q

Single largest metabolic disorder?

A

Glucose 6 Phosphate dehydrogenase

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16
Q

G6PDD genetically is ….

A

X linked recessive

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17
Q

What is G6PD responsible for?

A

oxidative step of pentose phosphate pathway

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18
Q

What type of cell in G6PDD pts is most affected?

A

Red blood cells because unlike other cells doesnt have other ways to handle oxidative stress

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19
Q

with G6PDD, there is a defect in ….

A

the ability to handle oxidative damage because there is reduced ability to produce NADPH, this is a potent reducer to protect against oxidative damage

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20
Q

G6PDD Pt suffers acute oxidative damage from exposure to moth balls, what could occur?

A

Hemolytic anemia - presents as jaundice (see in newborns with G6PDD), paleness, dark urine, fatigue, shortness of breath/rapid heart rate, splenomegaly

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21
Q

Galactosemia pts are deficient in …

A

galactose 1-phosphate uridyl transferase

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22
Q

Galactosemic newborn presents with

A

vomiting, lethargy, failure to thrive and jaundice within the second week of life

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23
Q

Untreated galactosemia leads to

A

mental retardation
cataracts
liver cirrhosis

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24
Hereditary Fructose intolerance is caused by?
deficiency in fructose-1-phosphate aldolase (Aldolase B) | leads to build up of Fructose in liver
25
Glycogen stores are largest in
liver and muscles
26
Congenital Adrenal Hyperplasia caused by
deficiency in 21-hydroxylase -90% MCC of ambiguous genitalia in FEMALE newborns salt losing form - presents 2-3 wks of life with circulatory collapse, hyponatremia, hyperkalemia
27
Androgen insensitivity syndrome
Receptor defective leaving pt unresponsive to testosterone leading to external female characteristics
28
Familial Hypercholesterolemia
Autosomal dominant single gene disorder | High morbidity and mortality rates via premature coronary artery disease
29
Familial Hypercholesterolemia is characterized by
problems with the LDL receptor which leads to increased endogenous synthesis of cholesterol
30
What issues can there be with receptors in FH?
reduced/defective biosynthesis reduced/defective transport abnormal binding of LDL by the receptor abnormal internalization of the receptor
31
Mucopolysaccharidoses are characterized by
skeletal, vascular or CNS along with coarsening of facial features
32
What is Mucopolysaccharidoses due to?
progressive accumulation of sulfated polysaccharides
33
Sanfilippo syndrome
Most common MPS | due to deficiency in any one of four enzymes involved in degradation of heparin sulfate
34
Most common Sphingolipidoses?
Tay Sachs - high incidence among Ashkenazi jews | Gaucher
35
Tay Sachs is due to...
deficiency in subunit of beta-hexosaminidase, this results in accumulation of sphingolipid GM2 ganglioside
36
What is a diagnostic clue for Tay Sachs?
presentation of characteristic cherry red spot in the center of the macula fundus
37
Gaucher is due to ....
glucosylceramide beta glucosidase
38
Lesch Nyhan syndrome
Hypoxanthine guanine phophoribosyltransferase (HGPRT) | leads to increased amounts of purines - see 200x higher levels - likely due to increased amounts of PRPP
39
Symptoms of Lesch Nyhan syndrome
``` uric acid crystals uncontrolled movements spasticity mental retardation compulsive self mutilation ```
40
Adenosine Deaminase Deficiency
inherited immunodeficiency | defect in adenosine deaminase - responsible for 15% of SCID - bubble boy disease
41
Adenosine deaminase is responsible for ...
conversion of AMP to IMP in purine salvage pathway | pts are severely deficient in both T and B cells, leaving them without functional immune system
42
Porphyrins are ...
ringed structures which can chelate metal ions
43
What are the two main phorphyrin functions?
liver - cytochromes in ETC and detox of substances | Erythrocytes - hemoglobin
44
Acute Intermittent Porphyria
due to deficiency uroporphyrinogen I synthase which leads to increased excretion of precursors porphobilinogen and S-aminolevulinic acid in urine
45
Congenital Erythropoietic Porphyria characterized by
extreme photosensitivity hemolytic anemia - most require multiple blood transfusions and splenectomy Red/brown discoloration of teeth which fluoresce red under UV light
46
Congenital Erythropoietic porphyria due to
deficiency in uroporphyrinogen III synthase | see build up of reticulocytes since body in need of RBCs
47
is there an effective treatment for PKU?
supplementation with PAH prove ineffective infant and child pts with PKU keep to strict diet low in phenylalanine after normal neural development can relax dietary restrictions
48
Oculocutaneous albinism results from . . . .
a deficiency of tyrosinase which converts Tyrosine to Melanin
49
Phenotype of Oculocutaneous albinism?
no melanin production leads to lack of pigment in hair, skin, iris, and ocular fundus of patients
50
What results from the lack of pigment seen in OCA?
leads to poor visual acuity, nystagmus (pendular eye movements) and underdevelopment of fovea
51
What characterizes OCA type 1?
mutation within tyrosinase gene on chromosome 11q | classic albinism - no measurable tyrosinase activity
52
What characterizes OCA type 2?
due to mutation in P gene (mouse homolog called pink eye) on chromosome 15q
53
Newborns with Maple syrup urine disease present with?
first week of life with vomiting, alternating tone if left untreated, then leads to death within a few weeks treatment involves dietary restriction of intake of V, I and L
54
What are some sources of oxidative damage?
infection - colds and flu Drugs - NSAIDS, quinolones, sulfa drugs, tylenol, drugs metabolized through liver, naphtalene (moth balls) and artifical food coloring Foods - fava beans and other legumes, sulfites, menthol-containing foods
55
Acute oxidative damage in pt with G6PDD can lead to ...
hemolytic anemia which presents with paleness, jaundice, dark urine, fatique, shortness of breath/rapid heart rate, splenomegaly
56
G6PDD is genetically ...
very diverse - more than 100 different mutations identified
57
symptoms of Hereditary fructose intolerance
presentation age varies depends on when foods with fructose are introduced into diet minimal to severe - failure to thrive, vomiting, jaundice, seizures
58
Von Gierke disease
glucose 6 phosphatase
59
Cori disease
amylo-1,6 glucosidase ( debrancher enzyme)
60
Anderson disease
glycogen brancher enzyme (synthesis enzyme) | impairs ability to build storage
61
Hepatic phosphorylase deficiency
multimeric enzyme complex with subunits coded for by autosomal and X linked genes
62
How does Von Gierke disease present?
hepatomegaly (seen when glycogen stores cannot be broken down) hypoglycemia in infants presents as sweating, fast heart rate
63
How does Cori disease present?
hepatomegaly | muscle weakness
64
How does Anderson disease present?
hypotonia, abnormal liver function within first year of life, progresses to liver failure quickly
65
How does Hepatic phosphorylase deficiency present?
hepatomegaly hypoglycemia failure to thrive
66
Which glycogen storage disease affects the liver and has no effective treatment?
Anderson disease
67
Pompe disease
glycogen storage disease that affects muscle | due to deficiency in lysosomal enzyme alpha 1,4 glucosidase which is necessary for glycogen breakdown
68
McArdle Disease
due to deficiency in muscle phosphorylase | necessary for breakdown of muscle glycogen during exercise
69
symptoms of Pompe disease
presents in infancy with hypotonia, delay in gross motor milestones, due to muscle weakness, eventually leads to enlarged heart and death from cardiac failure within first 2 years no current treatment
70
symptoms of McArdle
presents in adolescence with muscle cramps during exercise | no effective treatmetn

CMBM exam 3 (24 decks)

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