1. INBORN ERRORS OF AMINO ACIDS METABOLISM
TYROSINE METABOLISM

2. Tyrosine
Tyrosine is formed from phenylalanine by phenyl alanine hydroxylase. During the reaction, BH4 is oxidized to dihydro - biopterin (BH2). Tyrosine, like cysteine, is formed from an essential amino acid and is, therefore, non essential only in the presence of adequate dietary phenylalanine.

3. tetrahydro-biopterin
Degradation of Phenylalanine to Tyrosine
The reaction requires molecular oxygen and the coenzyme tetra hydrobiopterin (BH4), which can be synthesized from guanosine triphosphate (GTP) by the body. One atom of molecular oxygen becomes the hydroxyl group of tyrosine, and the other atom is reduced to water. During the reaction, BH4 is oxidized to dihydro - biopterin (BH2). BH4 is regenerated from BH2 by NADH-requiring dihydro pteridine reductase.
+O2
tetrahydro-biopterin
PA hydro-xylase

6. homogentisate oxidase
Degradation of TYROSINE & Aromatic Amino Acids
Acetoacetate, fumarate, and pyruvate — are common intermediates.
Molecular oxygen is used to break an aromatic ring.
homogentisate oxidase
fumarylacetoacetase

7. INBORN ERRORS OF AMINO ACIDS METABOLISM
Alcaptonuria - inherited disorder of the tyrosine metabolism caused by the absence of homogentisate oxidase.
homogentisate is accumulated and excreted in the urine
turns a black color upon exposure to air
In children:
urine in diaper may darken
In adults:
darkening of the ear
dark spots on the on the sclera and cornea
arthritis

8. Aortic valve stenosis in alcaptonuria
Accumulation of oxidized homogentisic acid pigment in connective tissue (ochronosis)
Aortic valve stenosis in alcaptonuria

9. Arthritis of the spine is a complication of alkaptonuria ochronosis

11. Albinism – genetically determined lack or deficit of enzyme tyrosinase
Phenylalanine
Tyrosine
Tyroxine
Melanin
DOPA
Dopamine
Norepinephrine
Epinephrine
Albinism – genetically determined lack or deficit of enzyme tyrosinase
Tyrosinase in melanocytes oxidases tyrosine to DOPA and DOPA-chinone

12. Symptoms of albinism:
inhibition of production or lack of melanin in skin, hair, eyes
increased sensitivity to sunlight
increased risk of skin cancer development
sun burns
photophobia
decrease of vision acuity
strabismus, nystagmus

13. Tyrosinemia is an extremely rare but treatable hereditary disorder
Tyrosinemia is an extremely rare but treatable hereditary disorder. When the body cannot break down tyrosine, high levels build up in the blood and form a toxic substance (known as succinylacetone) in the liver, kidneys, and central nervous system. This means that if tyrosinemia isn't treated, it may cause liver and kidney damage and brain-related problems, such as problems with learning.
There are three types of tyrosinemia. The type a child has depends on which enzyme they are lacking. Children with tyrosinemia type 1 (HT-1) are deficient in an enzyme called fumarylacetoacetate hydrolase. If not recognized and treated right away, the condition could be fatal for a child at an early age. However, with treatment, tyrosine levels in the blood can be managed.
Dietary restriction of tyrosine and phenylalanine in the treatment of hereditary tyrosinemia type 1 (HT-1).

14. A deficiency of the enzyme fumarylacetoacetase leads to an accumulation of the novel and extremely toxic compound succinylacetone

15. Tyrosinaemia type 1
A deficiency of the enzyme fumarylacetoacetase leads to an accumulation of the novel and extremely toxic compound succinylacetone . This is detected by urine organic acid analysis. Tyrosine concentrations in body fluids are also elevated but can be variable.
Affected children typically present with severe liver disease and renal Fanconi syndrome.
The drug nitisinone inhibits an enzyme higher in the pathway, 4 hydroxyphenylpyruvate dioxygenase. This
prevents the synthesis of succinylacetone and dramatically improves prognosis. Patients continue to
need dietary therapy to prevent tyrosine accumulation.