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Flashcards in Inborn Errors Of Metabolism Deck (25):

What are the main organic acidemias?


Glutaric acidemia
Isovaleric acidemia
Methylmalonic acidemia
Propionic acidemia


What are the features of organic acidemias?

Glucose: Low
NH3: High
Ketones: Yes
Acidosis: Yes
Lactate: High

- DOL 2
- Thrombocytopenia, granulocytopenia
- Dx: urine organic acid levels
- Tx: hydration, stop protein intake, IV glucose and ammonia scavengers, L-carnitine


What are the features of urea cycle defects?

Glucose: Nml
NH3: High!!! (low BUN)
Ketones: No
Acidosis: No
Lactate: Nml

- OTC, Citrullinemia, ASA

- Hypotonia
- Respiratory alkalosis
- Vomiting
- Lethargy
- Dx: check serum citrulline, arginine, ASA, urine orotic acid. low arginine, no citruline, high urine orotic acid.
- Tx: restrict protein, NH3 scavengers (benzoate, phenylbutarate)


What are the features of fatty acid metabolism disorders?

Glucose: Low
NH3: Nml/High
Ketones: No
Acidosis: Mild
Lactate: High

- Induced by stress, fasting -> nonketotic hypoglycemia
- Do not present in the first week of life
- Possible hepatomegaly with transaminitis
- Dx: low glucose and low ketones. Get carnitine and acylcarnitine levels.
- Tx: IV glucose


What are the features of storage diseases?

Glucose: Low
NH3: Nml
Ketones: Yes
Acidosis: Yes (gap acidosis)
Lactate: High

- GSD1, GSD2

- Organomegaly (from glycogen buildup)
- Dx: low fasting glucose + ketones
- Tx: cornstarch


What are the features of mitochondrial disorders?

Glucose: Low
NH3: Nml
Ketones: Yes
Acidosis: Yes
Lactate: High

Same as storage disorders

- Elevated pyruvate level, lactic acid level, uric acid level


What are the features of amino acidopathies?

Glucose: Nml
NH3: Nml
Ketones: No
Acidosis: No
Lactate: Nml (except in MSUD)

- Subtypes: "PATH"
A: Alkaptonuria
T: Tyrosinemia
H: Homocysteinuria

- Dx: high levels of specific amino acid that cannot be broken down in serum and urine
- Tx: Limit intake of specific amino acid


What are the features of hyperglycinemia?

Glucose: Nml
NH3: Nml
Ketones: No
Acidosis: No
Lactate: Nml

- Seizures, hiccups, lethargy
- Dx: high glycine
- poor prognosis


What are the features of galactosemia?

Glucose: Low
NH3: Nml
Ketones: Nml
Acidosis: No
Lactate: Nml

- GALT deficiency
- Patients present with GNR sepsis
- Can present with vomiting, diarrhea, lethargy, hepato-megaly, jaundice, hypoglycemia, seizures
- Dx: high g1p, non-glucose reducing substances in urine, low GALT activity in RBCs
- Tx: lactose and galactose free diet


What are the features of isovaleric acidemia?

Sweaty feet smell
Poor feeding
Prone to getting infections
No lactic acidosis
Treatment: protein restriction


What are the features of methylmalonic acidemia and propionic acidemia?

Poor feeding

MMA: tx with B12
Propionic: tx with biotin


What are the features of ornithine transcarbamylase deficiency?

- X-linked (much more symptomatic in boys than in girl carriers, who only get symptoms when they are sick)
- High urine orotic acid


What are the features of von Gierke's disease?

- Glucose-6-phosphatase deficiency -> can't break down glycogen -> glycogen deposits in organs
- Doll like face
- Only presents when there is hypoglycemia
- Hypoglycemia, ketoacidosis (from fat breakdown), lactic acidosis, hyperuricemia
- Tx: low carb diet, complex carbs (cornstarch)


What are the features of Pompe disease?

- Lysosomal disorder: deficiency of lysosomal alpha 1,4 glucosidase
- Presentation: baby with hypotonia, macroglossia, and hypertrophic cardiomyopathy
- Glycogen deposits in organs -> organomegaly
- No hypoglycemia because other glycogen stores can be broken down
- Dx: ⬆️ glycogen in lysosomes, ⬆️ LDH, ⬆️ CK


What are the aminoacidopathies?

"PAM is a Hot tamale."

P: Phenylketonuria
A: Alkaptonuria
M: Maple syrup urine disease
H: Homicysteinuria


What are the features of PKU?

- Musty/mousy order
- Light colored skin and hair
- Developmental delay -> severe MR
- Possible eczema like rash
- Septal defects
- Dx: no tyrosine
- Tx: low phenylalanine diet (overtreating-> lethargy, rash, diarrhea)
- If pregnant women don't control diet -> microcephaly, congenital heart defects, cognitive defects


What are the features of alkaptonuria?

- Problem with phenylalanine and tyrosine metabolism
- Black urine
- Excess homogentisic acid deposits in joints and heart valves
- Dx: homogentisic acid levels in urine
- Tx: limit intake of phenylalanine and tyrosine


What are the features of maple syrup urine Disease?

- Early presentation (first week of life)
- Sweet smelling urine, tachypnea, lethargy, untreated -> encephalopathy, seizures
- High ammonia, high ketones, hypoglycemia
- Dx: serum with high levels of VIAL (valine, isoleucine, alloisoleucine, leucine)
- Tx: diet free of branched-chain amino acids


What are the most common lysosomal storage diseases?

H: Hurler, Hunter
N: Niemann-Pick
T: Tay-Sachs
G: Gaucher


What are the features of mucopolysaccharidoses?

- Hunter and Hurler syndromes
- Due to a missing or dysfunctional lysosomal enzymes needed to break down a long carbohydrate
- Result in the accumulation of dermatin, keratin, and heparin sulfate in the brain, bones, connective tissue, and other organs
- Progressive physical deformities and cognitive problems
- Coarse features, thick eyebrows, organomegaly, progressive joint contractures, growth deceleration, progressive deafness
- Dx: excessive urine mucopolysaccharides


What is the difference between hunter syndrome and hurler syndrome?

Hunter syndrome has no corneal clouding.

- Imagine X Marks the Spot. A Hunter has good vision, so he can make the kill by aiming for the X.


What are the features of Tay-Sachs disease?

- Autosomal recessive
- Deficiency of Hexosaminidase A enzyme
- Develop normally until about nine months
- Macrocephaly, exaggerated startle reflex, cherry red spot on the retina, death by age 4
- No organomegaly


What are the features of Gaucher disease?

- Hepato-megaly, thrombocytopenia, easy bruisability, osteosclerosis and lytic lesions with bone pain, short stature


What are the features of Fabry disease?

- Opacities of that eye, vascular disease of the kidney, heart or brain, orange colored skin lesions, no organomegaly

Foam cells / Febrile episodes
Alpha galactosidase A deficiency / Angiokeratomas
Burning pain in hands and feet (peripheral neuropathy)
Renal failure
YX genotype (male, X-linked recessive)
Ceramide trihexoside accumulation


What are the features of Niemann-Pick disease?

“Nieman Marcus is so fancy, they replaced all of their escalators with CHERRY RED SPHINGO SLIDES. You jumped on, but smashed your belly, causing HSM and hit your head at the bottom, causing NEURO DEFICITS.”

- Sphingomyelinase deficiency
- Accumulation if sphingomyelin in macrophages within the liver and lungs
- Neurologic problems, hepatosplenomegaly, cherry red spot