Alkaptonuria : A Genic endelian Abnormality

Genic Mendelian Abnormality

In genetic Mendelian disorders, one disorder or the other occurs due to a mutation in the gene. Alkaptonuria is also an example of this. It is only a disorder in the metabolic process of Phenylalanine, as we read in Phenylketonuria. Regulation of metabolism is done by different enzymes at each stage and different enzymes are produced by different genes. On this basis, 'Beadle and Tatum' propounded the 'one gene, one enzyme' hypothesis.

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If the condition of the gene changes in any one phase or more than one phase, then distortion is seen in the human body. This is called Genic Mendelian Abnormality. Alkaptonuria is also caused by dysfunctional gene activation in the next step of metabolism in Phenylketonuria.

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Alkaptonuria

• This is also due to homozygous recessive genes.
• It was first studied by Garrod.
• In the normal state of Phenylalanine metabolism, the amino acid Tyrosine is formed from Phenylalanine. Which usually produces Homogentisic acid or Alkapton in the presence of dominant gene. In its next step, homogentisic acid breaks down into CO2 and H2O in the presence of enzymes.
• Whereas in abnormal condition, due to the recessive gene of Homogentisic acid or Alkapton, necessary enzyme is not available in the above process and thus Homogentisic acid or Alkapton is not metabolized and its The concentration goes on increasing in the blood and it is excreted in the urine, which turns black when it comes in contact with air. This condition is called Alkaptonuria.
• Homogentisic acid is also called Alkapton, that is why this disorder is called Alkaptonuria.
• It also causes arthritis.
• In this, the cartilaginous parts of the body gradually turn black.

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