Inherited disorders:
- Absence of protein ex agammaglobulinemia
- Abnormal protein ex sickle cell anaemia
- Defective receptors ex familial hypercholesterolaemia
- Defective carrier proteins ex cystinuria
- Absence of enzyme ex phenylketonuria
Treatment strategy for inherited disorders:
- Supply missing product
- Restrict intake of substrate
- Increase excretion of toxic products
- Replace the missing enzyme
- Replace the abnormal gene
Phenylketonuria:
- autosomal recessive inheritance
- Incidence: 1:10000 birth
- Deficiency: phenylalanine hydroxylase
Functions of Tyrosine - Used to synthesise: Clinical features of PKU:
- Tissue proteins - Vomiting
- Melanin - Irritability
- Thyroxine - Poor feeding
- catecholamines - Pale skin
- - Eczema
Hyperphenylalaninemia - high serum [phenylalanine] causes brain damage by: - Blue eyes
- Interfering with brain amino acid metabolism - Fair hair
- Inhibition of neurotransmitter release - Mental retardation
Diagnosis of PKU:
- (High) serum [phenylalanine] > 700 umol/L (normal < 100umol/L)
Management of PKU:
- Restrict dietary intake of phenylalanine
- Ensure adequate tyrosine intake
- Absence of protein ex agammaglobulinemia
- Abnormal protein ex sickle cell anaemia
- Defective receptors ex familial hypercholesterolaemia
- Defective carrier proteins ex cystinuria
- Absence of enzyme ex phenylketonuria
Treatment strategy for inherited disorders:
- Supply missing product
- Restrict intake of substrate
- Increase excretion of toxic products
- Replace the missing enzyme
- Replace the abnormal gene
Phenylketonuria:
- autosomal recessive inheritance
- Incidence: 1:10000 birth
- Deficiency: phenylalanine hydroxylase
Functions of Tyrosine - Used to synthesise: Clinical features of PKU:
- Tissue proteins - Vomiting
- Melanin - Irritability
- Thyroxine - Poor feeding
- catecholamines - Pale skin
- - Eczema
Hyperphenylalaninemia - high serum [phenylalanine] causes brain damage by: - Blue eyes
- Interfering with brain amino acid metabolism - Fair hair
- Inhibition of neurotransmitter release - Mental retardation
Diagnosis of PKU:
- (High) serum [phenylalanine] > 700 umol/L (normal < 100umol/L)
Management of PKU:
- Restrict dietary intake of phenylalanine
- Ensure adequate tyrosine intake
