Organic Acids

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created 8 years ago by chemistry_goo
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1

clinical features of all organic aciduria

vomitting, enurological decompensation, failure to thrive (don't eat as much because it makes them sick) and unusual odors

2

laboratory features of organic acidurias

metabolic acidosis
ketonuria
hypoglycemia
hyperammonemia
thrombocytopenia
amino aciduria, organic aciduria

3

How are these diagnosed?

urine organic acid analysis by gas chromatography/mass spectrometry

4

What are the branched chain amino acids that are affected in Maple syrup urine disease

leucine, isoleucine and valine

5

what enzyme is affected in MSUD and what does it normally do?

decarboxylation by branched chain alpha ketoacid dehydrogenase (with TPP cofactor)

6

how is MSUD treated?

with dietary restriction of branched chain amino acids

7

What builds up in MSUD?

The alpha keto acids after the deamination step of the amino acid is what builds up. But because this reaction is reversible, the build up causes it to go backwards and the corresponding amino acid builds up

8

what form of heterogeity does MSUD present?

genetic heterogeneity, different mutations on different genes all give you MSUD

9

which form of MSUD is the most common/severe?

the classical form -- E1 alpha subunit

10

What compound can be looked for to detect MSUD in amino acid profile?

alloisoleucine which is a different isoform that shouldn't be there

11

What accumulates in isovaleric acidemia

isovaleryl coA, isovaleric acid, isovaleryl glycine

12

clinical presentation of isovaleric acidemia

acute -- emesis, acidosis, sweaty feet smell

chronic -- developmental delay

13

what feeds into the pathway of propinoyl coa to succinyl coa

Cholesterol

Valine
Odd chain fatty acids
Met
isoleucine
threonine

14

Propionic Acidemia

isolated or part of multiple carboxylase deficiency

15

methylmalonic acidemia

primary due to methylmalonyl coA mutase deficiency or secondary if cofactor deficiency B12

16

Biotinidase

all 4 carboxylases are deficient

17

what are the 2 mutants of methlymalonyl coA deficiency

Mut 0 - no activity even with cofactor, CRM - '

Mut - = decreased activity, due to decreased affinity for cofactor, and reduced stability CRM +

18

what is the cofactor for methylmalonyl coA

Cobalamin

19

what are the 2 enzymes that use cobalamin and what types of cobalamin do they each use

methylmalonyl coA --> adenosylcobalamin
and methlycobalamin ---> methylcobalamin

20

a problem with adenosylcobalamin causes what?

methylmalonic acidemia

21

a problem with methylcaobalamin causes what?

homocysteinuria with low methionine

22

what does CblA and CblB abormality cause?

abnormalities in Adenosyl Cbl syntehsis only = clinical and biochemical picture identical to mut defects, isolated MMA

23

CblC and CblD and CblF abnormality cause?

impaired synthesis of both adenosyl and methylcobalamin, so both MMA and homocystinuria

24

what are secondary findings of methylmalonyl coA mutase deficiency?

hypoglycemia, mild hyperlacticacidemia, hyperammonemia, hyperglycinemia,

25

what is the primary finding of methylmalonyl coA mutase deficiency

methylmalonic aciduria

26

what 4 enzymes is biotin required for?

propinoyl coA
methylcrotonyl coA
pyruvate
acetyl coA

Carboxylase

27

what enzyme puts biotin on the apoenzyme?

holocarboxylase synthetase

28

what enzyme recycles biotin from enzymes

biotinidase

29

what are symptoms of biotinidase deficiency?

neurological (siezures, developmental delay, hypotonia)
dermatological (alopecia, dermatits)

30

when does the disease present typically?

usually presents later on because the baby is born with the mother's biotin