Inborn Errors of Metabolism (IEM) Flashcards
(39 cards)
How many people are affected by inborn metabolic diseases?
1: 1-2000 live births.
- most present in childhood
What causes inborn metabolic diseases?
Genetic defects of metabolic pathways.
What type of genetics is concerned with genetic disorders that affect metabolic pathways?
Biochemical genetics.
How can enzyme deficiencies be problematic? (2)
- Less metabolite produced (deficiency)
- Accumulation of substrate (toxic)
What are the main mechanisms of metabolic diseases? (3)
- Accumulation of toxin
- Energy deficiency
- Deficient production of essential metabolite
What substance accumulates in patients with urea cycle defects?
Ammonia.
-ammonia is not converted to urea sufficiently
What are the main clinical effects of hyperammonaemia (^ammonia)?
- Lethargy
- Poor feeding
- Vomiting
- Tachypnoea
- Convulsions
- Death
What substance accumulates in porphyrias?
Porphyrins.
What pathway is blocked in porphyrias?
Blockage of haem production pathway.
Outline the haem production pathway.
ALA >>PBG >> uroporphrin >> coproporphrin >> protoporphrin >> haem.
What are the main 2 types of porhyrias?
- Acute porphyria
- Photosensitive porphryia
What substrates are in excess in acute porphyria? (2)
- ALA
- PBG
What substrates are in excess in photosensitive porphyria? (3)
- Uroporphrin
- Coproporphrin
- Protoporphrin
What are the possible signs of acute porphyrias?
- Severe abdominal pain
- Pain in chest//legs/back
- Constipation/diarrhoea
- Insomnia/anxiety
- Vomiting
- High BP
- Mental changes
- Seizures
What are the possible signs of photosensitive porphyria?
- Sensitivity to light
- Sudden painful erythema/oedema
- Slow-healing blisters
- Fragile, itchy skin
- Increased hair growth
What is a symptom present in both acute and photosensitive porphyria?
Red/brown urine.
What is a major defect of energy deficiency?
Defects in fatty acid oxidation.
|»_space; crisis presentations
What is the general process of fatty acid oxidation?
Fatty acids
» fatty acid oxidation
» acetyl coA
»ketones (outside mitochondria) / TCA cycle
Where does the majority of fatty acid oxidation take place?
Mitochondria.
What is the effect of defects in fatty acid oxidation?
Decreased ketones.
What can cause deficient production of essential metabolite/structural components?
Defective receptors.
What can deficient production of essential metabolite/structural components lead to?
Androgen insensitivity syndrome.
-due to defective receptors
What are androgens?
Males sex hormones.
-e.g. testosterone
What is androgen insensitivity syndrome?
Genetically male persons is resistant to male hormones.
|»_space; female phenotype, but the genetic makeup of a man
