Nitrogen 3 Flashcards
What are inherited metabolic disorders?
Group of genetic diseases involving metabolic defects
What are interited metabolic disorders usually due to?
A single gene
What do inherited metabolic disorders usually result in?
Deficiencies of key enzymes
What does the deficiency of key enzymes cause?
Abnormal synthesis of proteins, amino acids, carbohydrates or lipids
Are inherited metabolic disorders common?
No, they are typically rare
What are the consequences of a key enzyme defect?
Decreased formation of desired product
Accumulation of substance before the enzyme with the defect
Increase formation of other, unwanted metabolites
What kind of inheritance do most inherited metabolic disorders show?
Autosomal reccesive inheritance
What does autosomal dominance inheritance look like?
What does autosomal recessive inheritance look like?
What are some common clinical features of inherited metabolic disorder presening in childhood?
Acidosis
Failure to thrive
Vomiting
CNS dysfunction
Hypoglycaemia
Unusual odour
Why do proteins need to be immedietely metabolised?
There is no storage facility like carbohydrates
Where does the urea cycle happen?
Split between the mitochondrial matrix and cytosol
What happens in the urea cycle?
Ammonia goes in and urea comes out
What are urea cycle defects?
Defects in any of the 6 enzymes involved
How many inherited disorders of the urea cycle are there?
6
What is the most common inherited urea cycle defect?
OTC deficiency
What kind of inheritance is OTC dificiency?
X linked inheritance
What inherited urea cycle defects have autosomal inheritance?
All of them apart from OTC dificiency
What does OTC dificiency cause?
Hyperammoniaemia, which is elevated blood ammonia which is highly toxic
What could amino acids be metabolised into?
Other amino acids
Hormones
Pigments
Neurotransmitters
What do inherited gene defects cause?
Decreased enzyme activity
What does decreased enzyme activity cause?
Decreased product
Increased precurder
Alternative metabolic products that may be toxic
What is phenylketonuria (PKU)?
Absence/dificiency of phenylalanine hydroxylase (PAH)
What kind of inherited disorder is PKU?
Autosomal recessive disorder
What does PKU cause?
Increased phenylalanine levels which is toxic, and the production of alternative metabolic products
What happens to untreated people with PKU?
Impaired brain development
What can the alternative metabolic products produced due to PKU do?
Cross the blood brain barrier and cause irreversible neurological damage
What are clinical factors of PKU?
Normal at birth
Phenylalanine rises rapidly after feeding is established
Delayed brain development visible by 6 months
How is PKU diagnosed?
Screening test
Confirmation of increased phenylalanine in the lab
Decreased blood tyrosine levels
What is the treatment of PKU?
Low protein diet
Maintain bloody phenylalanine levels
Maintain blood tyrosine levels at the upper limit
