lecture 10; biomedical genetics Flashcards
what is an IEM
inborn error of metabolism
how do we classify IEMs
- identifying which metabolites are high or low
- identify which pathway is disrupted
- enzyme; which is not working
- organelle involved; where abouts in the cell is it
diagnostic tests for IEMs
- screening tests
- stress tests
- specific assays
- post mortem protocol
which of these diagnostic tests would you use to detect many conditions
screening tests
which of these diagnostic tests would you use when there is an idea for a disease
specific assays
what are urea cycle defects
affect the bodies ability to remove ammonia from the bloodstream
failure to breakdown amino acids means they remain in the body as ammonia and this buildup of ammonia can cause brain damage, coma and if untreated can be fatal
symptoms of urea cycle defects
poor feeding
vomiting
seizures
lethargy (lack of energy)
what can be done to treat urea cycle defects
bringing the level of protein down with a high carb, low protein diet
phenylketonuria
disorder resulting from the lack of phenylalanine hydroxylase (PAH)
the lack of PAH leads to a build up of phenylalanine in the blood and brain causing health problems
if phenylketonuria is untreated what can it cause
dev. delays
seizures
behavioral problems
how is phenylketonuria treated
diet low in phenylalanine which involves restricting foods high in protein
treatment of IEMs
- decrease substrate
- excrete toxic metabolite
- replenish missing product
- increase substrate
- block production of toxic metabolites
how would you decrease the substrate
dietary restriction of substrate
- Management of PKU typically involves reducing the intake of dietary phenylalanine through a special low-protein diet a
prevent absorption of substrate from gut
examples of replenishing the missing product as a treatment of IEMs
- give carbs in glycogen storage disease
- give tyrosine in PKU
- give intermediates in urea cycle
talk about increasing the substrate as a method of treatment for IEMs
usually used when the metabolic pathway is blocked by the deficiency of an enzyme
name a lysosomal storage disorder
Hunter Syndrome also known as MPS II
what is the cause of Hunter syndrome/MPS II
accumulation of glycosaminoglycan
What is a way of treating MPS II/ Hunter Syndrome
treatment with bone marrow transplant can reduce symptoms
lipoprotein metabolism - familial hypercholesterolemia
rare autosomal dominant type of disorder characterised by high levels of low- density lipoprotein cholesterol in the blood
lipoprotein metabolism link to coronary artery disease
50% of males and 25% of women with lipoprotein metabolism have CAD by 50
treatment of lipoprotein metabolism
statins (meds to lower cholesterol)
dietary restrictions
plasmapheresis (procedure to remove and replace blood plasma from the body)
carbohydrate metabolism - galactosemia: what are the symptoms in new borns
vomiting
jaundice
food refusal
hepatomegaly (enlarged liver)
lethargy (fatigue)
edema
treatment of galactosemia
avoiding lactose, fruit and veg
newborn screening - rationale for screening
- it must be a disease that lots are screening for
- the test must be useful
- the disease must be easily identified
- parents must be able to give consent
what are the pros and cons of having a low threshold for screening
miss no cases but there are many false positives
what are the pros and cons of having a high threshold for screening
you miss cases but there are few false positives
name some diseases that are currently screened for
PKU
Galactosaemia
maple syrup urine disease
cystic fibrosis
MCADD
