Nitrogen 3 Flashcards

1
Q

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

A

Amino acids
Proteins
Carbohydrates
Lipids

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2
Q

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

A

Infancy or childhood

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3
Q

What type of inheritance pattern do IMD’s follow?

A

Autosomal recessive inheritance

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4
Q

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

A

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

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5
Q

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

A

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

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6
Q

Where in the cell is the urea cycle?

A

It is split between the cytosol and the mitochondria

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7
Q

How many enzymes catalyse the reaction in the liver?

A

5

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8
Q

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

A

The quantity of protein in the diet

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9
Q

What is the regulatory enzyme in the urea cycle?

A

CPS1 - Carbomyl Phosphate synthase

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10
Q

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

A

N Acetylglutamtae

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11
Q

How many inherited disorders of the urea cycle exist?

A

6

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12
Q

Describe the inherited metabolic disorder associated with OTC?

A

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

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13
Q

What may amino acids be metabolised into?

A

Other amino acids, hormones, neurotransmitters, pigments

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14
Q

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

A

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

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15
Q

What enzyme is deficient or absent in phenylketonuria?

A

Phenylalanine hydroxylase (responsible for converting phenylalanine to tyrosine)

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16
Q

What type of inheritance is PKU?

A

Autosomal recessive

17
Q

Why are high levels of phenylalanine bad?

A

Toxic - can result in impaired brain development

18
Q

What is the treatment?

A

Reduced protein diet wupplemented with tyrosine

19
Q

What are the clinical features of PKU?

A

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
Q

How is diagnosis achieved of PKU?

A

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

21
Q

When are babies screened for PKU?

A

Neonatal screening - day 5