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1.5 Amino Acidopathies (PKU, MSUD, Alkaptonuria, histidinemia)
Terms in this set (11)
inborn = congenital
Human diseases that affect the metabolism of the amino acids catabolism.
defective enzymes of aa may cause the accumulation of :
- aa derivatives or
to the point that they may become toxic.
can lead to (rare):
-appropriate nutritional support
- careful monitoring
normal Phe Hydroxylase (PheH): makes
DoPA -->to Melanin
[Phe ---(PheH)> tyrosine
(using NADPH, and O2)
(release H2O, NADP+)
Tyrosine ---(Tyr.H) --> 3,4,Dihydroxy-Phe --->->->
a dark brown to black pigment occurring in the hair, skin, and iris of the eye in people and animals. It is responsible for tanning of skin exposed to sunlight.
Pathway see page. 2
inherited defect in the gene that codes for phenylalanine hydroxylase.
without Phe Hydroxylase:
(Phe can't convert to tyr.)
(if Phe hydroxyls present these 2 are low)
fair hair, light skin, blue eyes
neurochemical causes is unknown:
perhaps lacking dopamine:
3,4-dihydroxy-Phenylalanine = Dopa.
- Mental retardation
- failure to walk or talk
- no growth
gross dev. disabilities to
no major Sx.
neurological Sx = not completely known.
PKU Dx & detection
detect: blood Phe level.
Most states requires
testing PKU of all newborn.
at birth, PKU = normal of Phe in blood (<2mg/dL).
after weeks, Phe increases
(12-15 mg/dL) ==> elevates Phe.Pyruvate (in urine).
Goal: Provide enough Phe to enable basic function to cont. but no excess.
excess can be fatal.
Blood Phe kept ~ 10mg/dL by feeding synthetic aa which is low in Phe,
supplement with low Phe in food.
Maple Syrup Urine Disease
Branched Chain Amino Acids
step 1: aminotransferase
step 2: BCAA Decarboxylase is defective
BCAA & their corresponding α-keto acid
all end up in urine.
smell of maple syrup.
- Severe brain damage
few survived beyond 1 year.
MSUD has a high mortality rate.
(egg white has BCAA)
and their corresponding
reduce only to certain extend to prevent a deficiency of BCAA.
fumarate and acetoacetate
once Homogentisic acid expose to air, air oxidizes it, and it turns black (urine black).
Cause & Clinical:
will increase URINE.
later, black pigment in cartilage and other connective tissues causing
treat Sx if needed.
no major treatment
(FIRST enzyme in the catabolism of histidine.)
more histidine in urine
mental retardation (common)
- difficult with speech & language skills
restrict histidine intake
(lower in blood)
- this may impair growth & development
these diseases varies from population to population
e.g. hetero mix-culture of NY. exhibits 1 in 180,000 case of histidnemia.
while homogenous of Japan, only 1 in 9600 cases
THIS SET IS OFTEN IN FOLDERS WITH...
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1.5 Amino Acid Metab
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