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Flashcards in Inborn errors of metabolism Deck (23):
1

what is an inborn error?

an inherited disorder that affects metabolism

2

what are IMDs

diseases due to:
- absense, inactivityor reduced activity
of enzymes or other proteins that reguatio metabolic pathways

3

what was Garrrods Hypothesis of IMDs

A --> A --> C and D
either of these may interfere with the metabolic process
if one thing isnt working properly it can cause levels of a toxic metabolite to build up

4

classifications of IMDs by affected molecule

carbohydrate
amino acid
organic acid
nucleic acid
glycosaminoglycans

5

classifications of IMDs by cell organelle

lysosomes
mitochondria
peroxisomes

6

classifications of IMDs by affected pathway

urea cycle
glyconeogenesis
fatty acid oxdation
krebs cycl
glycosaminoglycan catabolism

7

when do IMDs present?

after the neonatal period as an acute, lifethreatening illness

8

how are IMDs recognised?

clinical symptoms are typically non specific and show up as somethin ele such as sepsis but the parents details are needed tp determine the likeihood of IMD

9

why is it important to recognise IMDs

- quick treatment to prevent long term damage
- benefit for the next child born

10

4 broad grops of IMD

- secondaary accumulation of toxins
- enery deprivation
- liver dysfunction with hypoglycaemiae
- dysmorphmism
(overlapping is common)

11

decribe secondary accumulation of toxins

enzyme converting A to B doesnt work
leads to B decreasing and A accuulating
A is then converted to something else, C which is toxic

12

clinical presentation of secondary accumulation of toxins

toxins take time to build up in system so can take a while to show
- intoxication, vomiting, coma, liver failure
- acidosis, ketosis

13

example of secndary accumulation of toxins

propionic acidaemia
enzyme to digest proten missing too much proprionic acid now which is toxic

14

describe energy deprivation IMD

symtoms due t defciency in the process of energy production or utilisation
ATP levels drop

15

clinical presentation of energy deprivation

hypoglycamiae and sudden death
all metabolic tissues affected
- floppiness
-lheart failre
- circulatory collapse
- failure to thrive
improvement after energy replacement such as glucose infusion
* also seen in adults after time of starvation

16

example of energy deprivation IMD

MCAD
medium-chain acyl CoA dehydrogenase deficiency
child already with the condition but unknow, fasts for a period of time and the condition now shows up as
prolonged fasting can leads to hypoglyasema and shock because fatty acids are being onvereted properly to energy and thins shut down

17

describe liver dysfunction/hypoglycaemia IMD

liver essential to maintain glucose levels,
ketones build up leading to actidosis and galactosaemia

18

what is galactosaemia

liver dysfunction
increased galactose because the enzyme covnerting this isnt working and it accumulates and this can be toxic

19

what is Hurlers syndrome

a dysmorphism IMD
- accumulation of lysosomes and storage affecting all organs and tissues

20

whats the role of labs in IMDs

- most will offer a routine set of tests to rule out IMDs
biochem labs do these tests
- staff should be educated in the types of IMD

21

what kind of approach is used for lab investigations of IMD

phase approach
- first line investigations of routinetests
- second line investigation more complex
- confirmatory tests

22

examples of first line investigations

serum glucose
metabolic acidosis
blood pH
organ function tests

23

examples of second line investiations

complex looking at several analytes
- plasma urine amino acid
- urine organic acids