Hello steemians !!!
I am back with very new and interesting topic. Have you ever heard about black urine disease?? If not, you are lucky that you are reading these lines ! Today you will be knowing one more disease than you have known before .
So, lets begin !!!

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"It is first error of metabolism ever identified"

WHAT IS BLACK URINE DISORDER??

Black urine disease ( commonly known as alkaptonuria ) is one of the genetic disorder. It is autosomal recessive disorder .
Prevalence is approx . 1 in 2,50,000.
It is a disorder in which body cannot process amino acid phenylalanine and tyrosine.

WHY DOES IT OCCUR ??

Before knowing this, it is very much important to know metabolism of phenylalanine and tyrosine. It is clearly shown below.

In alkaptonuria , there is mutation of HGD gene which codes for the enzyme homogentisate 1,2-dioxygenase .
Due to mutation in both copies of DNA ( one from mother and one from father ) it is unable to produce homogentisate 1,2 dioxygenase. So, homogentisic acid is unable to convert into maleyl acetoacetic acid ( it is shown above ). This leads to the accumulation of homogentisic acid . The blood level of homogentisic acid will then increase. Later it will be excreted on urine (which turn urine black after being exposed to air).

Homogentisate is oxidized by polyphenol oxidase to benzoquinone acetate, which undergo polymerization to form alkapton bodies. It is deposited in cartilage of ear, nose and joint ( this condition is called onchronosis ).

SYMPTOMS OF ALKAPTONURIA ???

1.Urine turn into black after exposing to air.
2.With advances in age features of osteoarthritis may be seen.
3.dark spots in the sclera.
4.black earwax
5.kidney stones and prostate stones
6.thickened and darkened cartilage of ears.

It can also lead to heart problem

TREATMENT

Basically there is not specific treatment.
1.You should take low protein diet.
2.Some doctor may suggest intake of vitamin C to decrease accumulation in cartilage.
3.Other treatment is focused in preventing

arthritis
heart disease
kidney stones

4.In recent time it is found that Nitisinone can be useful in treating these disorder. It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase which is responsible for converting tyrosine to homogentisic acid. So the production and accumulation of HGA is decreased.

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SOURCE

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That's it for today. I will come with next topic in comming days.
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