Inborn Errors: Amino Acidopathies Flashcards Preview

DEMS Unit 2 Part 2 > Inborn Errors: Amino Acidopathies > Flashcards

Flashcards in Inborn Errors: Amino Acidopathies Deck (19):
1

Liver Failure

Inborn errors:
- fructosemia, galactosemia, alpha-1-antitrypsin, tyrosinemia type 1, hemochoromatosis

2

Elevated tyrosine and methionine; abundance of succinylacetone and delta-aminolevulinic acid

Tyrosinemia Type 1

Deficiency of fumarylacetoacetate hydrolase deficiency

-Common in Finland
- AR

3

3 presenting forms of tyrosinemia type 1

1. Early in infancy - liver disease
2. Late infancy - Rickets due to renal tubulopathy with no obvious liver failure
3. Porphyria-like attack at any age

4

Succinylacetone ___ delta aminolevulinic acid dehydratase activity

inhibits

causes porphyria like abdominal pain crises and peripheral neuropathy

5

alpha fetoprotein

- unreliable as a marker in neonates
- otherwise marker of liver regen

6

Tx of Tyrosinemia type 1

1. 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexane-dione (NTBC)
- Inhibits 4-hydroxyphenylpyruvic acid dioxygenase, increases plasma tyrosine, decreased production of FAA and succinylacetone
2. Phe and Tyr restriction
3. Liver transplant if hepatocellular carcinoma develops

7

Palmoplantar keratosis

Tyrosinemia Type 1

8

Alkaptonuria

1. Black urine
2. Black pigmentation of cartilage and collagen
3. Degenerative arthritis from 4th decade

9

Hypermethioninemia

1. deficiency of CBS
2. Accumulation of homocysteine and an elevation in methionine

Methionine is a 2ndary marker

10

Diagnostic eval of hypermethioninemia

1. Labs:
- elevated methionine, elevated homocystine, urine homocystine, urine organic acids normal, cyanide-nitroprusside test positive

2. Marfan like skeletal malformations, osteoporosis, scoliosis, most common in B6 non-responsive forms

Risk for recurrent VTE and premature atherosclerotic disease, eye abnormalities

11

Classical homocystinuria

- AR inheritance
- 1/200,000
- Often missed on newborn screens
- 50% are B6 responsive (do a B6 challenge)

12

Tx of homocystinuria

1. Restrict dietary protein
2. supplemented with methionine free medical foods
3. Oral betaine
4. Consider supplementation with B12, folate, and/or cysteine

Can give B6 if it is responsive

13

Is ammonia only elevated in UCD?

No, also secondarily elevated in other inborn errors of metabolism

Avoid valproate in these pts at all costs!

14

Triggers of hyperammonemia

- infection
- fever
- vomiting
- GI or other bleeding
- decreased energy or protein intake (fasting)
- Chemo
- catabolism
- exercise
- Drugs

15

OTC deficiency

1. Most common disorder
2. X-linked disorder
3. Males first 2-3 days of life and usually fatal.
4. Females get a range based upon pattern of X-inactivation

Don't forget to explore FHx!

16

OTC blood gas

Respiratory alkalosis
Plasma ammonia elevated
Tachypneic

17

OTC metabolites

1. Low citrulline
2. High glutamine
3. Elevated orotic acid

18

Ammonia Scavenging Agents

1. Sodium phenylacetate
2. Sodium Benzoate

19

UCD Tx strategies

- Dietary protein restriction
- ammonia scavenging meds
- L-arg or L-citrulline supplementation
- Hemodialysis or intravenous scavengers
- Consider liver transplantations