Alkaptonuria Disorder

Principal of Inheritance and variations

ALKAPTONURIA

It is an gene mutation in autosome recessive type. The metabolic defect is the deficiency of homogenticis acid oxidase enzyme. It's an autosomal recessive condition. It is compatible with fairly normal life.

First inborn metabolic disorder described by A. Garrod. 

CAUSE- Defect in the enzyme homogentisate oxidase, that catalysed oxidation of homogentisate to maleylactoactate. 

Homogentisate accumulates in blood and body tissues and is excreted in large amounts in urine.

CHARACTERISTICS FEATURE-

1. The urine of alkaptonuria patients become Dark after being exposed to air.

2. The alkapton imparts a characteristic black-brown color to urine. 

3. Alkaptonuria is a harmless condition.

4. Later in life deposition of dark colored alkapton pigments in connective tissues and bones occur.

5. This results in black pigmentation of the sclera, ear, nose and cheeks and the clinical condition is known as Ochronosis.

6. Ochronosis leads to tissue damage and may develop joint pain, arthritis and backache.

DIAGNOSIS-

1. The urine sample of patients of alkaptonuria turns dark on standing in air.

2. The urine gives positive test with ferric chloride and silver nitrate due to reducing activity of homogentisate.

3. Benedict's test is strongly positive.

TREATMENT-

1. Since alkaptonuria is not considered life threatening, this condition is not treated.

2. Later in life, the Symptoms of arthritis may be treated but the condition itself is not.

3. No specific treatment is required.

4. But minimal protein intake with phenylalanine less than 500gm/day is recommended.

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