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Pediatrics > Genetic disorders of Metabolism > Flashcards

Genetic disorders of Metabolism Flashcards

1
Q

Phenylketonuria

  • what is it
  • genetics
  • presentation
  • dx
  • tx
A

Defect hydroxylation phenylalanine –> tyrosine

AR trait

Nl at birth until buildup toxic metabolites

  • mental retardation
  • vomiting (projectivle)
  • eczematous rash
  • musty odor
  • fair haired + skinned + blue eyes

Dx

  • Blood screening after 48-72 hrs of life after protein intake
  • High phenylalanine, normal tyrosine
  • Guthrie test to detect metabolic products of phenylalanine in urine

Tx

  • diet low in phenyalanine
  • eat tyrosine

Complications:

  • infants born to moms with uncontrolled PKU –> risk MR, microcephaly, congential heart dz
  • high rate of spontaneous abortions
  • screen babies for 2-3 days after birth (nl if mom is ok since they have maternal enzymes)
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2
Q

Galactosemia

  • etiology
  • presentation
  • dx
  • tx
A

Deficiency of galactose-1-phosphate uridyl transferase
Galactose 1 phosphate accumulates

–> Kidney, liver, brain, injury

AR inherit

Sx: jaundice, vomiting, cataracts, HSM, E. coli sepsis

Dx:

  • newborn screening
  • reducing substances in urine

Tx:
- galactose elim

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3
Q

Ways to remember lysosomal storage diseases

A

Gaucher and Krabbe are friends
- gluco vs galacto

Taysachs and N-P are friends cause they have cherry red foveas

  • but TaysaX lacks heXosaminidase deficiency
  • you never PICK your nose with your sphinger (sphingomyelinase deficiency for Neimann pick)
  • but your liver is BIG with NP

Fabry likes ACTs = deficiency in a-galactosidase A, accumulates ceramide trihexoside

Metachromatic leukodystrophy like ARYLcs = deficiency in arylfulfatase A, accumulates cerebroside sulfate

FABRY is the only X linked recessive - all other are AR

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4
Q

Hepatomegaly

Aseptic necrosis of femur

Bone crises

Xray = erlenmeyer flask appearance of long bones

A

Gaucher’s disease

Autosomal Recessive

Also have gaucher’s cells - macrophages looking like crumpled tissue paper

Confirm with absence of glucocerebrosidase in leukocytes, skin fibroblasts, and liver cells

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5
Q

Gaucher’s disease

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
Glucocerebrosidase

Accumulate:
Glucocerebroside

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6
Q

Peripheral neuropathy

Developmental delay

Optic atrophy

Globoid cells

Opsithotonus

A

Krabbe’s disease

Autosomal Recessive

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7
Q

Krabbe’s disease

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
Galactocerebrosidase

Accumulate:
Galactocerebroside

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8
Q

Progressive neurodegeneration

Hepatosplenomegaly

Cherry red spot on macula

A

Neimann Pick disease

Autosomal recessive

Also have foam cells

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9
Q

Neimann-Pick disease

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
Sphingomyelinase

Accumulate:
Sphingomyelin

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10
Q

Progressive neurodegeneration

Developmental delay

Cherry red spot on macula

NO hepatosplanomegaly

A

Tay Sachs disease
Also in sandoff disease

Autosomal recessive

Also have lysosomes w/ onion skin

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11
Q

Tay Sachs disease

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
Hexosaminidase A

Accumulates:
GM2 ganglioside

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12
Q

Peripheral neuropathy of hands/feet

Angiokeratomas

Cardio/renal disease

A

Fabry’s disease

X linked recessive

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13
Q

Fabry’s disease

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
a-galactosidase A

Accumulate:
Ceramide trihexoside

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14
Q

Central and peripheral demyelination w/ ataxia

Dementia

A

Metachoromatic leukodystrophy

Autosomal recessive

  • neurodegen disorder of white matter
  • problems with myelin metabolism
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15
Q

Metchromatic leukodystrophy

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
Arylsulfatase

Accumulate:
Cerebroside sulfate

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16
Q

Developmental delay

Gargoylism

Airway obstruction

Corneal clouding

HSM

A

Hurler’s syndrome

Autosomal recessive

17
Q

Hurler’s syndrome

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
a-L-iduronidase

Accumulate:
Heparan sulfate
Dermatan sulfate

18
Q

Aggressive behavior

NO corneal clouding

Mild:
Developmental delay
Gargoylism

A

Hunter’s syndrome

X linked recessive

You can’t have corneal clouding to see as a HUNTER as you aim for the X

19
Q

Hunter’s syndrome

  • deficiency enzyme
  • accumulated substance
A

Deficiency:
Iduronate sulfatase

Accumulate:
Heparan sulfate
Dermatan sulfate

20
Q

Carnitine deficiency

A

Inability to transport long chain fatty acids into mitochondria to get broken down

Causes:

  • weakness
  • hypotonia
  • hypoketotic hypoglycemia
21
Q

Alkaptonuria

A

Autosomal recessive

Congenital deficiency of homogentisic acid oxidase

Can’t degrade tyrosine –> fumarate

Benign disease

Findings:

  • dark connective tissue
  • brown pigmented sclera
  • urine turns black on prolonged exposure to air
  • can have arthritis –> hoomogentisic acid toxic to cartilage
22
Q

Essential fructosuria

A

AR

Defect in fructokinase

Benign, asymptomatic

23
Q

Fructose intolerance

A

AR

Deficiency of aldolase B

Hypoglycemia
Jaundice
Cirrhosis
Vomiting

Tx:
- decrease fructose and sucrose intake

24
Q

Galactokinase deficiency

A

AR

Deficiency of galactokinase

MIld condition
Infantile cataracts

25
Q

Classic galactosemia

A

AR

Absence of galactose-1-phosphate uridyltransferase

Present in 1st wk of life

FTT
Jaundice
Hepatomegaly
Infantile cataracts
MR

Tx:
- no galactose and lactose in diet

26
Q

Ornithine transcarbamoylase deficiency

A

1 urea cycle disorder

X linked recessive

Can’t eliminate ammonia

Increased orotic acid in blood and urine

Dec BUN

Sx of hyperammonemia (tremor, somnolence, vomiting)

Tx:

  • supplement with citrulline
  • protein restrict
27
Q

Homocystinuria

A

AR

Can’t convert Homocysteine –> Cystathione

3 forms:

  • cystathione synthase deficiency
  • dec affinity of cystathione syntahse for B6
  • Homocysteine methyltransferase deficiency

Cysteine becomes essential!!

  • NOrmal at birth
  • Increased homocysteine in urine
  • MR
  • strokes***
  • Marfanoid habitus
  • downward dislocation of lens

Tx:

  • give high doses of B6
  • restric methionine
  • supplement cysteine
28
Q

Cystinuria

A

AR

Defect of renal tubular AA for cysteine, ornithine, lysine, arginine in PCT

Tx:

  • good hydration
  • urinary alkalinization
29
Q

Maple syrup urine disease

A

AR

Blocked degradation of branched amino acids (Ile, Leu, Val)

  • CNS defects
  • MR
  • Death
30
Q

Hartnup disease

A

AR

Defective neutral aa transporter on renal and intestinal epithelial cells

Tryptophan excretion in urine and dec absorption in gut

Leads to pellagra!!!

31
Q

Von Gierke’s disease

A

AR

Glycogen storage disease

Findings:

  • severe fasting hypoglycemia
  • inc glycogen in liver –> hepatomegaly
  • inc blood lactate
  • hyperURICemia
  • hyperLIPIDemia
  • nl LFTs
  • fat cheeks
  • thin extremities
  • short stature
  • protuberant abdomen
  • nl spleen and heart

Deficiency:
- Glucose-6-phosphatase

32
Q

Pompe’s disease

A

AR
= Acid maltase deficiency

Findings:

  • Cardiomegaly
  • early death
  • hepatomegaly
  • floppy baby w/ feeding difficulties
  • macroglossia

Deficiency:
- lysosomal a-1,4 glucosidase

33
Q

Cori’s disease

A

AR

Findings:

  • friends with Von Gierke but not as bad!
  • increased LFTs
  • normal blood lactate + uric acid
  • splenomegaly
  • nl kidneys

Deficiency:
- debranching enzyme

Gluconeogenesis ok

34
Q

McArdle’s disease

A

AR

Findings:

  • increased glycogen in muscle but can’t break down
  • painful muscle cramps
  • myoglobinuria w/ exercise lots

Deficiency:
- muscle glycogen phosphorylase

35
Q

Marfan features
MR
Thromboembolic events
Downward dislocation of lens

A

Homocystinuria

Pediatrics (17 decks)

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