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Flashcards in Nitrogen 3 Deck (21)
1

Inherited metabolic disorders usually result in abnormal synthesis and catabolism of:

Amino acids
Proteins
Carbohydrates
Lipids

2

When are symptoms of an inherited metabolic disorder usually most severe?

Infancy or childhood

3

What type of inheritance pattern do IMD's follow?

Autosomal recessive inheritance

4

What are some of the most common clinical features of inherited metabolic disorders present in childhood?

Acidosis
Failure to thrive
Vomiting, refusal of feeds, vomiting
Central nervous system dysfunction
Hypoglycaemia
Unusual odor

5

What happens to ingested protein that is surplus to the bodies needs? Why?

It is catabolised because there is no storage facility for excess proteins.

6

Where in the cell is the urea cycle?

It is split between the cytosol and the mitochondria

7

How many enzymes catalyse the reaction in the liver?

5

8

What does the concentration of the enzymes controlling the urea cycle depend on?

The quantity of protein in the diet

9

What is the regulatory enzyme in the urea cycle?

CPS1 - Carbomyl Phosphate synthase

10

What is the allosteric activator of CPS1? (Carbomyl phosphate synthase)

N Acetylglutamtae

11

How many inherited disorders of the urea cycle exist?

6

12

Describe the inherited metabolic disorder associated with OTC?

Deficiency in ornithine transcarbamoylase
Present in 1 in every 40000 births in the UK
X - Linked, meaning the male is hemizygous to the gene mutation.
Characterised by hyperannomaenia which is elevated blood ammonia level - highly toxic
Medical emergency
Usually present in newborn period

13

What may amino acids be metabolised into?

Other amino acids, hormones, neurotransmitters, pigments

14

What do inherited gene defects in the amino acid conversion pathway result in?

Decreased enzyme activity
Decreased product
Increased precursors
Alternative metabolic products, potentially toxic

15

What enzyme is deficient or absent in phenylketonuria?

Phenylalanine hydroxylase (responsible for converting phenylalanine to tyrosine)

16

What type of inheritance is PKU?

Autosomal recessive

17

Why are high levels of phenylalanine bad?

Toxic - can result in impaired brain development

18

What is the treatment?

Reduced protein diet wupplemented with tyrosine

19

What are the clinical features of PKU?

Normal Phe levels at birth, Phe levels rise rapidly once feeding is introduced
Days 3 and 4 may present feeding difficulties
Delayed mental development and neurological features are present by 6 months of age
Musty odor

20

How is diagnosis achieved of PKU?

Positive screening test
Quantitive amino acid analysis
Confirmation of increased blood Phe levels
Typically a decrease in blood tyrosine levels

21

When are babies screened for PKU?

Neonatal screening - day 5