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Define inherited metabolic disorder

Metabolism disorder caused by mutation in gene that codes for enzyme resulting in enzyme deficiency and breakdown of metabolic pathway


What are the 6 clinical presentations in neonates of IEMs and 5 in young children?

1. Vomiting
2. Seizures
3. Irritability
4. Poor feeding
5. Breathing disorder
6. Abnormal tone

1. Recurring vomiting
2. Dysmorphic features: characteristic facial expression
3. Mental retardation
4. Seizures
5. Developmental delay: milestones


What are the 7 categories of IEMs?

1. AA metabolism disorders
2. Carbohydrate metabolism disorders
3. FAO disorders
4. Lysosomal storage disorders
5. Peroxisomal disorders
6. Urea cycle disorders
7. Mitochondrial disorders


What is Von Gierke's disease?

IEM characterised by deficiency of glucose-6-phosphatase
Renders glycogen stores of body inaccessible
Lack free glucose
Glucose synthesis from glucose-6-phosphate via gluconeogenesis hampered


What are the affects of Von Gierke's disease?

1. Hypoglycaemia
2. Lactic acidosis
3. Hepatomegaly


Describe galactosaemia

Deficiency of galactose-1P uridyltransferase
Converts galactose-1P to glucose-1P which is subsequently converted to 6P and enters glycolysis


What are the effects of galactosaemia?

Child unable to utilise galactose component of lactose in milk
Accumulation of galactose-1P in blood, diarrhoea, vomiting, mental retardation, develop cataracts


What is the result of a deficiency of liver fructokinase or fructose-1P aldolase?

Fructokinase: convert fructose to fructose-1P
Fructose-1P aldolase: fructose-1P to glyceraldehyde

Fructose intolerance
Results in an accumulation of fructose-1P which inhibits both glycogenolysis and gluconeogenesis leading to hypoglycaemia


What are 2 AA metabolism disorders?

Alkaptonuria: black urine
Maple syrup urine disease


Describe alkaptonuria

Defect in breakdown of tyrosine and phenylalanine
Causes accumulation of homogentisic acid which is excreted in urine and oxidises on standing giving urine black colour

This can lead to arthritis due to build up in cartilage


Describe maple syrup urine disease

Defect in branched AA metabolism causing accumulation of keto-acids in urine

If left unmanaged can lead to physical and mental retardation


Describe phenylketonuria

Defect in phenylalanine hydroxylase causes impaired conversion of phenylalanine to tyrosine

Phenylalanine accumulates in blood and excreted in urine (aminoaciduria)


What are the signs of phenylketonuria?

Mental retardation
Red. melanin formation


What are the 6 presentations of phenylketonuria?

1. Mental retardation
2. Hypopigmentation
3. Developmental delay
4. Musty odour
5. Autism
6. Epilepsy


What is familial hypercholesterolaemia?

Disorder caused by red. number functional LDL receptors in liver


What are the 3 effects of hypercholesterolaemia and treatment options?

1. Premature coronary heart disease
2. Tendon xanthomas
3. Severe hypercholesterolaemia

Modify diet, fibrates, statins, bile acid binding resins