TYROSINEMIA.pptx

Tyrosinemia - protein metabolic disorder
Types of tyrosinemia
Symptoms
Causes

1. TYROSINEMIA BY: K.P.LAKSHANA, I M.Sc Home Science- Nutrition and Dietetics

2. Tyrosinemia : Tyrosinemia or  tyrosinaemia  is an error of metabolism, usually inborn, in which the body cannot effectively break down the amino acid tyrosine.  All tyrosinemias result from dysfunction of various genes in the phenylalanine and tyrosine catabolic pathway, and are inherited in an autosomal -recessive pattern. Types: Type 1 tyrosinemia Type 2 tyrosinemia Type 3 tyrosinemia Hereditary tyrosinemia

3. T ype 1 tyrosinemia: It is also called as tyrosinosis or hepatorenal tyrosinemia. It is an autosomal recessive disorder due to the deficiency of the enzyme fumaryl acetoacetate hydrolase . Acute tyrosinosis - Infants exhibit diarrhoea , vomiting, a cabbage like odour . They do not thrive well and there is usually associated liver damage. Infants die from liver failure. Untreated acute tyrosinosis cases do not survive and death occurs within 6 to 8 months.

4. Chronic tyrosinosis - Clinical features are similar but milder symptoms and course. Children survive and in untreated cases leads to death by the age of 10 years. In both types, plasma tyrosine levels are elevated (6-12mg/dl). There also occurs increase in plasma methionine level. Treatment- involves a diet low in phenylalanine and tyrosine and sometimes also low in methionine .

5. Type 2 tyrosinemia: Also known as Richnar- Hanhart syndrome. Enzyme deficiency- hepatic transaminase. Clinical findings- mental retardation ( mild to moderate), skin lesions and eye lesions, some infants may exhibit self mutilation and disturbances in fine coordination. Blood- plasma tyrosine level is elevated to 4 to 5mg/dl. Urine- tyrosine is excreted in urine, urinary concentration is elevated. But renal clearance and reabsorption of tyrosine falls within normal limits. Other metabolites excreted in urine are tyramine and N- acetyl tyrosine.

6. Neonatal tyrosinemia Maybe seen in premature infants. This is due to the absence of the enzyme Para- hydroxyphenylpyruvate hydroxylase. Blood levels of tyrosine and phenylalanine are elevated. Increased excretion of tyrosine, tyramine, p- OH phenyl acetate, and N- acetyl tyrosine in urine. Treatment- involves feeding a diet low in protein, specially with low phenylalanine and tyrosine. In premature infants administration of vitamin C may improve the condition.

7. Hereditary tyrosinemia An uncommon inherited disorder due to the deficiency of the enzyme p-OH- phenyl pyruvate oxidaase. Biochemical features similar to neonatal tyrosinemia but it differs as follows: Proportion of excretion of p-OH phenyl lactic acid is more. It is not suppressed by vitamin C administration.

8. Usually death ensues before 6 months due to liver failure. Those who survive develops later on: Nodular cirrhosis Multiple defects in tubular reabsorption like proteinuria, amino aciduria, and hyperphosphaturia Tendency to develop hypoglycaemia A number of patients develop hypophosphataemic rickets Hepatic carcinoma may develop in some cases as a late life complication.