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Aubf > Amino Acid Disorders > Flashcards

Amino Acid Disorders Flashcards

1
Q

The most well known of the aminoacidurias

A

Phenylketonuria

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2
Q

estimated to occur in 1 of every 10,000 to 20,000 births

A

Phenylketonuria

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3
Q

if undetected, results in severe mental retardation

A

Phenylketonuria

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4
Q

first identified in Norway by Ivan Følling in 1934, when a
mother with other mentally retarded children reported a
peculiar mousy odor to her child’s urine

A

Phenylketonuria

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5
Q

mousy odor in urine

A

Phenylketonuria

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6
Q

increased amounts of keto acids including phenylpyruvate

A

Phenylketonuria

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7
Q

normal conversion of phenylalanine to tyrosine is disrupted

A

Phenylketonuria

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8
Q

Interruption of the pathway also produces children with fair complexions—even in dark-skinned families—owing to the decreased production of tyrosine and its pigmentation metabolite melanin

A

Phenylketonuria

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9
Q

caused by failure to inherit the gene to produce the enzyme phenylalanine hydroxylase

A

Phenylketonuria or PKU

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10
Q

The gene is inherited as an autosomal recessive trait with
no noticeable characteristics or defects exhibited by heterozygous carriers

A

Phenylalanine hydroxylase

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11
Q

major constituent of milk and contained large amounts in aspartame

A

phenylalanine

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12
Q

Initial screening for PKU goes undetected in the urinalysis lab as the increased blood levels of phenylalanine must occur before urinary excretion of phenylpyruvic acid

A

2-6 weeks

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13
Q

In PKU, blood is collected

A

24 hours after birth

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14
Q

Phenylalanine can be detected as early as

A

4 hours after birth, and if cutoff values are lowered from 4 mg/dL to 2 mg/dL

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15
Q

BOY or GIRL: escape detection of PKU during early tests because of slower rises in blood phenylalanine levels

A

Girl

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16
Q

Newborn Screening Act of 2004

A

RA 9288

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17
Q

RA 9288 offers

A

expanded NBS will be offered as OPTIONAL to parents in all participating facilities
550 pesos for the initial 6 test
1500 pesos for the full complement of disorder

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18
Q

currently being used in screening for inherited disorders in newborns and has the ability to detect more than 25 different genetic disorders with a single specimen. This method is replacing the multiple procedures currently used in newborn screening programs

A

Tandem Mass Spectrometry (MS/MS)

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19
Q

reference method for quantitative serum phenylalanine

A

High Performance Liquid Chromatography (HPLC)

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20
Q

urine testing using ferric chloride may be used as a follow-up test to ensure proper dietary control in previously diagnosed cases and as a means of monitoring the dietary intake of pregnant women known to lack phenylalanine hydroxylase (5 drops of 10% ferric chloride to urine containing phenylpyruvic acid produces BLUE-GREEN COLOR)

A

FeCl3 Tube Test

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21
Q

a semiquantitative, bacterial inhibition assay for phenylalanine
that uses the ability of phenylalanine to facilitate bacterial growth(Bacilus subtilis) in a culture medium with an inhibitor (ꞵ-2-thienylalanine)
+ for Phenylketonuria = GROWTH

A

Guthrie test

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22
Q

provide false negative results due to the infant not being at least 24 hours old, which ensures adequate time for enzyme and amino acid levels to develop, and due to the sample not being taken before the administration of antibiotics or transfusion of blood or blood products

A

Guthrie Test

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23
Q

Treatment of PKU

A

High-protein foods, such as meat, fish, poultry, eggs, cheese, and milk, are avoided.

calculated amounts of cereals, starches,
fruits, and vegetables, along with a milk
substitute, are usually recommended

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24
Q

first drug to help manage PKU

The drug helps reduce
phenylalanine levels by increasing the activity of the PAH enzyme

A

Kuvan (sapropterin dihydrochloride)

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25
Q

The accumulation of excess tyrosine in the plasma (Tyrosinemia)

A

Tyrosyluria

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26
Q

may result from either
inherited or metabolic defects

A

Tyrosyluria

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27
Q

urine may contain excess tyrosine or its *degradation products

A

Tyrosyluria

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28
Q

degradation products in Tyrosyluria

A

p-hydroxyphenylpyruvic acid and p-hydroxyphenyllactic acid

29
Q

seen in premature infants, which is caused by underdevelopment of the liver function required to
produce the enzymes necessary to complete the tyrosine metabolism

A

transitory tyrosinemia

30
Q

acquired severe liver disease also produces

A

tyrosyluria

31
Q

rarely seen tyrosine and leucine crystals may be observed during microscopic examination of the urine sediment

A

Tyrosyluria in acquired severe liver disease

32
Q

Treatment of Tyrosinemia

A

Low-protein diet

Nitisinone (NTBC)

full or partial liver transplant

33
Q

Urine testing for tyrosinemia using nitroso-naphthol & ferric chloride test

A

nitroso-naphthol (+ orange-red color)

ferric chloride test (+ transient green)

34
Q

produces a generalized renal tubular disorder and progressive liver failure in infants soon after birth

A

Tyrosinemia Type 1

35
Q

caused by low levels of the enzyme
fumarylacetoacetate hydrolase

A

Tyrosinemia Type 1

36
Q

caused by lack of the enzyme tyrosine aminotransferase

A

Tyrosinemia Type 2

37
Q

Persons develop corneal erosion and lesions on the
palms, fingers, and soles of the feet believed to be caused by crystallization of tyrosine in the cells.

A

Tyrosinemia Type 2

38
Q

caused by lack of the enzyme p-hydroxyphenylpyruvic acid dioxygenase

A

Tyrosinemia Type 3

39
Q

result in mental retardation if dietary restrictions of
phenylalanine and tyrosine are not implemented

A

Tyrosinemia Type 3

40
Q

a second metabolic pathway also exists for tyrosine

A

Melanuria

41
Q

This pathway is responsible for the production of melanin, thyroxine,
epinephrine, protein, and tyrosine sulfate

A

Melanuria

42
Q

major concern of the urinalysis laboratory is melanin

A

Melanuria

43
Q

pigment responsible for the dark color of hair, skin, and eyes

A

melanin

44
Q

Deficient production of melanin results in

A

albinism

45
Q

Elevated urinary melanin is a serious finding that indicates

A

proliferation of the normal
melanin-producing cells (melanocytes) producing malignant
melanoma

46
Q

These tumors secrete a colorless precursor of melanin

A

5,6-dihydroxyindole,
which oxidizes to melanogen and
then to melanin, producing the characteristic dark urine

47
Q

one of the six original inborn errors of metabolism described by Garrod in 1902

A

Alkaptonuria

48
Q

derived from the observation that urine from patients with this condition darkened after becoming alkaline from standing at room temperature

A

Alkaptonuria

49
Q

“Alkaptonuria” was derived from

A

“alkali lover”

50
Q

the third major defect in the phenylalanine-tyrosine pathway and occurs from failure to inherit the gene to produce the enzyme homogentisic acid oxidase

A

Alkaptonuria

51
Q

Without this enzyme, the phenylalanine-tyrosine pathway cannot proceed to completion, and homogentisic acid accumulates in the blood, tissues, and urine

A

homogentisic acid oxidase

52
Q

observations of brown-stained or black-stained cloth diapers and
reddish-stained disposable diapers have been reported

A

Alkaptonuria

53
Q

In later life, brown pigment becomes deposited in the body tissues (particularly noticeable in the ears). Deposits in the cartilage
eventually lead to arthritis. A high percentage of persons with
this condition develop liver and cardiac disorders

A

Alkaptonuria

54
Q

Urine test for (homogentisic acid)

A

Ferric chloride test (Transient deep blue color)

Clinitest (yellow precipitate)

55
Q

Urine test for Alkaptonuria

A

Ferric chloride test
- BISHOP: black
- STRASINGER: transient deep blue

Clinitest/Benedict’s test
- yellow precipitate

Homogentisic acid test
- black

56
Q

Treatment for Alkaptonuria

A

high-dose vitamin C

57
Q

a lifelong and potentially life-threatening inherited metabolic disorder.
Metabolic disorders cause problems with how the body
breaks down food into the tiny components it uses for
energy.

A

Maple syrup urine disease (MSUD

58
Q

the body has trouble breaking down amino acids, the building blocks of protein

A

Maple syrup urine disease (MSUD

59
Q

In MSUD, the amino acids that are not broken down are:

A

Leucine
Isoleucine
Valine

60
Q

It affects about 1 in every 185,000
babies born worldwide

Autosomal recessive trait

A

MSUD

61
Q

Types of MSUD

A

Classic
Intermediate
Intermittent
Thiamin-responsive

62
Q

the most severe type.
It’s also the most common. Symptoms usually develop within the first three days of birth.

A

Classic MSUD

63
Q

This type of MSUD is less severe than classic MSUD.
Symptoms typically appear in children between 5 months and 7
years old.

A

Intermediate MSUD

64
Q

Children with this type of MSUD develop as expected until an infection or period of stress causes symptoms to appear.
People with this type of MSUD usually tolerate higher levels of the
three amino acids than those with classic MSUD

A

Intermittent MSUD

65
Q

This type of MSUD responds to treatment using high doses of vitamin B1 (thiamine) along with a restricted diet.

With treatment, people with this type of MSUD have a higher tolerance for the three amino acids

A

Thiamine-responsive MSUD

66
Q

absence or greatly reduced activity of the enzyme branched-chain
⍺-ketoacid decarboxylase complex

A

MSUD

67
Q

characteristics of MSUD

A

maple syrup or burnt sugar odor of the urine, breath, and skin

68
Q

Urine test for MSUD

A

2,4-dinitrophenylhydrazine (DNPH) or Brady’s test
- yellow turbidity or precipitate

69
Q

Management and Treatment of MSUD

A

Limited protein intake (meat, dairy, legumes)

Amino acid monitoring (leucine, isoleucine, valine)

cure: liver transplants

For emergencies:
- Glucose (as 10% dextrose) and insulin
- Nasogastric feeding tube (delivers particular nutrients)
- Hemodialysis
- Monitoring for signs of brain swelling or infection and acid buildup

Aubf (8 decks)

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