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3. Metabolism > Amino Acid Disorder > Flashcards

Amino Acid Disorder Flashcards

1
Q

[Met/AAD/PKU]

Enzyme deficient in phenylketonuria?
Causal gene for phenylalanine hydroxylase deficiency?
Percentage of phenylketonuria due to phenylalanine hydroxylase deficiency?

A

Phenylalanine hydroxylase
PAH
98% (Tetrahydrobiopterin (BH4) deficiency 2%)

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2
Q

[Met/AAD/PKU]

Biochemical diagnosis of phenylalanine hydroxylase deficiency? (3)

A

Plasma phenylalanine > 2 mg/dL (120 mmol/L)
Abnormal ratio of phenylalanine to tyrosine (>3, normal <1)
Normal BH4 cofactor, dihydropterine reductase

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3
Q

[Met/AAD/PKU]

Target phenylalanine concentration in management for phenylalanine hydroxylase deficiency?

A

2-6 mg/dL (120 - 360 mmol/L)

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4
Q

[Met/AAD/PKU]

Dietary agents to avoid in phenylalanine hydroxylase deficiency other than Phe restriction? (2)

A

Aspartame
Artificial sweetener that contains phenylalanine

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5
Q

[Met/AAD/PKU]

Other cause of pheynylketonuria than phenylalanine hydroxylase deficiency?

A

Tetrahydrobiopterin (BH4) deficiency

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6
Q

[Met/AAD/PKU]

Newborn screening measures ___, ___ and ___ ratio for phenylketonuria

A

Phenylalanine and Tyrosine, the ratio

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7
Q

[Met/AAD/PKU]

Symptoms of phenylketonuria if untreated? (5)
- Skin, smell (3)
- Neurologic (2)

A
  1. Musty body order
  2. Eczema
  3. Decreased skin and hair pigmentation
  4. Epilepsy, Intellectual disability, behavioral problems
  5. Parkinson-like features
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8
Q

[Met/AAD/PKU]

Teratogenic effect of phenylketonuria if untreated? (6)

A
  1. Recurrent spontaneous abortion
  2. Microcephaly, intellectual disability, behavioral problems
  3. Congenital heart defect
  4. Tracheoesophageal fistula
  5. Limb malformations
  6. Intrauterine growth restriction
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9
Q

[Met/AAD/PKU]

Brain MRI finding shows ___
Mechanism is because ___

A

Progressive white matter disease (without neurologic deterioration)

Phe prevents myelination

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10
Q

[Met/AAD/PKU]

Usual Phe level in classic, untreated phenylketonuria?

A

> 20 mg/dL (1200 mmol/L)

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11
Q

[Met/AAD/PKU]

Complications due to restricted diet in phenylketonuria? (2)

A

Osteopenia
Vitamin B 12 deficiency

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12
Q

[Met/AAD/PKU]

Cofactor that can be treated with in phenylketonuria?

A

Sapropterin (B6BH4, Kuvan)

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13
Q

[Met/AAD/PKU]

Highest prevalent population for phenylalaine hydroxylase deficiency?

A

Turks 1:2,600
Irish 1:4,500

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14
Q

[Met/AAD/PKU]

Biochemical process that BH4 involved other than Phenylalanine? (3)

A

Catecholamine
Serotonin
Nitric oxide

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15
Q

[Met/AAD/PKU]

Clinical findings of Tetrahydrobiopterin (BH4) deficiency compared to PKU? (3)

A
  1. Microcephaly, epilepsy, intellectual disability, abnormal movements
  2. Recurrent hyperthermia without infections
  3. Hypersalivation, and swallowing difficulties
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16
Q

[Met/AAD/PKU]

Foods that high in Phenylalanine?

A

Meat, beans, tofu, milk, pasta, sweat potatos

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17
Q

[Met/AAD/PKU]

Phenylalanin level for mild hyperphenylalaninemia (HPA)?

A

Phe on unrestricted diet between 2 and 10 mg/dL

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18
Q

[Met/AAD/Tyrosinemia]

Types of tyrosinemia? (3)

A

Hereditary tyrosinemia type 1 (hepatorenal tyrosinemia)
Tyrosinemia type 2 (oculocutaneous tyrosinemia)
Tyrosinemia type 3

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19
Q

[Met/AAD/Tyrosinemia]

Causes of elevated tyrosine other than enzyme defects? (3)

A

Transient tyrosinemia (Infancy, delayed maturation)
Scurvy
Liver diseases

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20
Q

[Met/AAD/Tyrosinemia]

Clinical presentation of untreated Tyrosinemia type I? (5)

A
  1. Growth failure
  2. Liver dysfunction
  3. Renal tubular dysfuction (Fanconi like renal syndrome)
  4. Neurologic crises: altered mental status, abdominal pain, peripheral neuropathy, and/or respiratory failure
  5. Rickets
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21
Q

[Met/AAD/Tyrosinemia]

Treatment for Tyrosinemia type I? (2)

A

Nitisinone (Orfadin)
Low-tyrosine diet

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22
Q

[Met/AAD/Tyrosinemia]

What is Nitisinone (Orfadin)?

A

Synthetic reversible inhibitor of Hydroxyphenylpyruvate dioxygenase
(parahydroxyphenylpyruvic acid dioxygenase (p-HPPD), prevents the accumulation of fumarylacetoacetate and its conversion to succinylacetone)

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23
Q

[Met/AAD/Tyrosinemia]

Tyrosinemia type 1

Enzyme defect?
Causal gene?

A

Fumarylacetoacetase (FAH)
FAH

24
Q

[Met/AAD/Tyrosinemia]

Biochemical tested in newborn screening for tyrosinemia type 1?

A

Succinylacetone

25
Q

[Met/AAD/Tyrosinemia]

Enzyme defect in tyrosinemia type 2?

A

Tyrosine aminotransferase

26
Q

[Met/AAD/Tyrosinemia]

Clinical findings of tyrosinemia type 2? (3)

A
  1. Corneal ulcers or dendritic keratitis
  2. Red papular or keratotic lesions on their palms and soles (due to tyrosine buildup)
  3. Intellectual disability
    (No liver toxicity, no succinylacetone)
27
Q

[Met/AAD/Tyrosinemia]

Enzyme defect in tyrosinemia type 3?

A

4-hydroxyphenylpyruvate dioxygenase

28
Q

[Met/AAD/Alkaptonuria]

Enzyme defect in alkaptonuria?

A

Homogentisate 1,2-dioxygenase

29
Q

[Met/AAD/Alkaptonuria]

Three major features of alkaptonuria?

A

Urine that turns dark on standing
Ochronosis (bluish-black pigmentation in connective tissue)
Arthritis of the spine and larger joints

30
Q

[Met/AAD/Alkaptonuria]

Other manifestations of alkaptonuria other than classic triad; dark urine, ochronosis, and arthritis? (3)

A
  1. Hypothyroidism
  2. Aortic or mitral valve calcification or regurgitation, aortic dilatation
  3. Renal stones, prostate stones
31
Q

[Met/AAD/MSUD]

Typical presentation of classic maple syrup urine disease by hours/days?
12-24 hours: ___
2-3 days: ___
4-6 days: ___
7-10 days: ___

A

12 - 24 hours: Elevated concentrations of branched-chain amino acids and alloisoleucine
2 - 3 days: Early and nonspecific signs of metabolic intoxication (i.e., irritability, hypersomnolence, anorexia)
Branched-chain alpha-ketoacids, acetoacetate, and beta-hydroxybutyrate in urine
4 - 6 days: Worsening encephalopathy manifests as lethargy, apnea, opisthotonos, and reflexive “fencing” or “bicycling” movements
The sweet maple syrup odor becomes apparent in urine
7 - 10 days: Severe intoxication culminates in critical cerebral edema, coma, and central respiratory failure

32
Q

[Met/AAD/MSUD]

Clinical presentation of intermediate maple syrup urine disease?

A

Severe metabolic intoxication and encephalopathy in the face of sufficient catabolic stress

33
Q

[Met/AAD/MSUD]

Treatment for maple syrup urine disease?

A

BCAA-free medical foods, Judicious supplementation with isoleucine and valine

34
Q

[Met/AAD/MSUD]

Clinical complications of treated adolescent/adult with maple syrup urine disease?

A

Attention-deficit/hyperactivity disorder, depression, and anxiety disorders

35
Q

[Met/AAD/MSUD]

Maple syrup urine disease

Enzyme defect?
Causal gene (2)?

A

Branched-chain alpha-ketoacid dehydrogenase complex (BCKD)

BCKDHA and BCKDHB
(Branched Chain Ketoacid DeHydrogenase)

36
Q

[Met/AAD/GA]

Two types of glutaric acidemia type 1?

A
  1. Infantile-onset disease
  2. Later-onset disease (after age 6 years)
37
Q

[Met/AAD/GA1]

Glutaric acidemia type 1

Enzyme defect?
Causal gene?

A

Glutaryl-CoA dehydrogenase
GCDH

38
Q

[Met/AAD/GA1]

Biochemical finding in newborn screening for glutaric acidemia type 1?

A

Glutarylcarnitine (C5DC)

39
Q

[Met/AAD/GA1]

Follow-up biochemical testing for abnormal newborn screening result for glutaric acidemia type 1? (2)

A

Urine organic analysis or
Quantitative glutaric and 3-hydroxyglutaric acid

40
Q

[Met/AAD/GA1]

Clinical finding in untreated infantile type glutaric acidemia type 1? (3)

A

Progressive macrocephaly
Generally normal development until crisis (febrile illness)
Acute encephalopathic crisis (hypotonia, loss of motor skills, feeding difficulty, and sometimes seizures) usually occurring in the setting of an intercurrent infectious illness, fasting, or other physiological stressor

41
Q

[Met/AAD/GA1]

Clinical finding in untreated late onset type glutaric acidemia type 1?

A

Nonspecific neurologic abnormalities including headaches, vertigo, dementia, and ataxia

42
Q

[Met/AAD/GA1]

Characteristic brain MRI finding for glutaric acidemia type 1? (4)

A
  1. Open opercula
  2. Ventriculomegaly
  3. Attenuated signal from basal ganglia (striatal degeneration)
  4. Subdural hemorrhage (or retinal hemorrhage)
43
Q

[Met/AAD/GA1]

Causal gene for glutaric acidemia type 1?

A

GCDH
(Glutaryl-CoA DeHydrogenase)

44
Q

[Met/AAD/GA1]

Management for glutaric acidemia type 1? (2)

A

Low-lysine diet
Carnitine supplementation

45
Q

[Met/AAD/Homocystinuria]

Classic homocystinuria

Synonym?
Causal gene?

A

Homocystinuria Caused by Cystathionine Beta-Synthase Deficiency

CBS
(Cystathionine b-Synthase)

46
Q

[Met/AAD/Homocystinuria]

Two phenotypes of classic homocystinuria (homocystinuria Caused by Cystathionine Beta-Synthase Deficiency)?

A

B6-responsive homocystinuria
B6-non-responsive homocystinuria

47
Q

[Met/AAD/Homocystinuria]

Four characteristics of classic homocystinuria (homocystinuria Caused by Cystathionine Beta-Synthase Deficiency)?

A

Involvement of the eye (ectopia lentis and/or severe myopia)
Skeletal system (marfanoid, excessive height, long limbs, scolioisis, and pectus excavatum)
Vascular system (thromboembolism)
CNS (developmental delay/intellectual disability)

48
Q

[Met/AAD/Homocystinuria]

Biochemical findings of homocystinuria?

A

Increased concentrations of plasma total homocysteine and methionine

49
Q

[Met/AAD/Homocystinuria]

Management for classic homocystinuria? (5)

A

Methionine-restricted diet
Vitamin B6 (pyridoxine) therapy (if shown to be B6 responsive)
Folate
Vitamin B12 supplementation
Betaine therapy (adolescent and adults)

50
Q

[Met/AAD/NKH]

Enzyme defect for nonketotic hyperglycemia?

A

Deficient activity of the glycine cleavage enzyme system (GCS)

51
Q

[Met/AAD/NKH]

Two types of nonketotic hyperglycemia?

A

Severe NKH (no developmental progress and intractable epilepsy)
Attenuated NKH (variable developmental progress and treatable or no epilepsy)

52
Q

[Met/AAD/NKH]

Characteristics of nonketotic hyperglycemia? (2)
- In utero
- Neonate

A

Hiccups in utero
Progressive lethargy evolving into profound coma and marked hypotonia in the neonatal period

53
Q

[Met/AAD/NKH]

Characteristic Biochemical finding for nonketotic hyperglycemia?

A

Increased ratio of CSF glycine to serum glycine

54
Q

[Met/AAD/NKH]

Treatment option for nonketotic hyperglycemia?

A

Sodium benzoate

55
Q

[Met/AAD/Alkaptouria]

[Amino Acid - Alkaptonuria]
Name for bluish-black pigmentation in connective tissue in Alkaptonuria?

A

Ochronosis

56
Q

[Met/AAD/PKU]

Age of onset of untreated classic phenylketonuria?

A

Normal at birth
Within a few months musty smell and seizure

57
Q

[Met/AAD/PKU]

Fetal exposure to uncontrolled Phenylketouria pregnant patients (5)?

A
  1. Intrauterine growth restriction
  2. microcephaly / brain malformations
  3. congenital heart defect
  4. limb malformations
  5. tracheoesophageal fistula

3. Metabolism (14 decks)

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