Nitrogen 3

Question 1

What are inherited metabolic disorders?

Answer 1

Group of genetic diseases involving metabolic defects

Question 2

What are interited metabolic disorders usually due to?

Answer 2

A single gene

Question 3

What do inherited metabolic disorders usually result in?

Answer 3

Deficiencies of key enzymes

Question 4

What does the deficiency of key enzymes cause?

Answer 4

Abnormal synthesis of proteins, amino acids, carbohydrates or lipids

Question 5

Are inherited metabolic disorders common?

Answer 5

No, they are typically rare

Question 6

What are the consequences of a key enzyme defect?

Answer 6

Decreased formation of desired product

Accumulation of substance before the enzyme with the defect

Increase formation of other, unwanted metabolites

Question 7

What kind of inheritance do most inherited metabolic disorders show?

Answer 7

Autosomal reccesive inheritance

Question 8

What does autosomal dominance inheritance look like?

Question 9

What does autosomal recessive inheritance look like?

Question 10

What are some common clinical features of inherited metabolic disorder presening in childhood?

Answer 10

Acidosis

Failure to thrive

Vomiting

CNS dysfunction

Hypoglycaemia

Unusual odour

Question 11

Why do proteins need to be immedietely metabolised?

Answer 11

There is no storage facility like carbohydrates

Question 12

Where does the urea cycle happen?

Answer 12

Split between the mitochondrial matrix and cytosol

Question 13

What happens in the urea cycle?

Answer 13

Ammonia goes in and urea comes out

Question 14

What are urea cycle defects?

Answer 14

Defects in any of the 6 enzymes involved

Question 15

How many inherited disorders of the urea cycle are there?

Answer 15

6

Question 16

What is the most common inherited urea cycle defect?

Answer 16

OTC deficiency

Question 17

What kind of inheritance is OTC dificiency?

Answer 17

X linked inheritance

Question 18

What inherited urea cycle defects have autosomal inheritance?

Answer 18

All of them apart from OTC dificiency

Question 19

What does OTC dificiency cause?

Answer 19

Hyperammoniaemia, which is elevated blood ammonia which is highly toxic

Question 20

What could amino acids be metabolised into?

Answer 20

Other amino acids

Hormones

Pigments

Neurotransmitters

Question 21

What do inherited gene defects cause?

Answer 21

Decreased enzyme activity

Question 22

What does decreased enzyme activity cause?

Answer 22

Decreased product

Increased precurder

Alternative metabolic products that may be toxic

Question 23

What is phenylketonuria (PKU)?

Answer 23

Absence/dificiency of phenylalanine hydroxylase (PAH)

Question 24

What kind of inherited disorder is PKU?

Answer 24

Autosomal recessive disorder

Question 25

What does PKU cause?

Answer 25

Increased phenylalanine levels which is toxic, and the production of alternative metabolic products

Question 26

What happens to untreated people with PKU?

Answer 26

Impaired brain development

Question 28

What can the alternative metabolic products produced due to PKU do?

Answer 28

Cross the blood brain barrier and cause irreversible neurological damage

Question 29

What are clinical factors of PKU?

Answer 29

Normal at birth Phenylalanine rises rapidly after feeding is established Delayed brain development visible by 6 months

Question 30

How is PKU diagnosed?

Answer 30

Screening test Confirmation of increased phenylalanine in the lab Decreased blood tyrosine levels

Question 31

What is the treatment of PKU?

Answer 31

Low protein diet Maintain bloody phenylalanine levels Maintain blood tyrosine levels at the upper limit