Why is alkaptonuria a recessive genetic disorder?
Why is alkaptonuria a recessive genetic disorder?
Alkaptonuria is a rare autosomal recessive disorder that is due to a mutation in the homogentisate 1,2 dioxygenase (HGD) gene, resulting in abnormalities of tyrosine catabolism and tissue deposition of homogentisic acid.
What is HGD gene?
The HGD gene provides instructions for making an enzyme called homogentisate oxidase, which is active chiefly in the liver and kidneys.
What chromosome is alkaptonuria located on?
On chromosome 3 there’s a gene with a special role in the history of genetics. It’s a gene associated with a disease called alkaptonuria, which turns urine black and earwax red. In 1902, Archibald Garrod noticed that this gene runs in families.
What is the characteristic feature of a patient with alkaptonuria?
The three major features of alkaptonuria are dark urine or urine that turns dark on standing, ochronosis (bluish-black pigmentation in connective tissue), and arthritis of the spine and larger joints.
What tests can be used to diagnose alkaptonuria?
Your doctor can use a test called gas chromatography to look for traces of homogentisic acid in your urine. They can also use DNA testing to check for the mutated HGD gene. Family history is very useful in making a diagnosis of alkaptonuria.
Is alkaptonuria dominant or recessive?
Alkaptonuria is inherited as an autosomal recessive trait. Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent.
Which enzyme is mutated in alkaptonuria?
Mutations in the HGD gene cause alkaptonuria. The HGD gene provides instructions for making an enzyme called homogentisate oxidase. This enzyme helps break down the amino acids phenylalanine and tyrosine, which are important building blocks of proteins.
What type of mutation is alkaptonuria?
Alkaptonuria is caused by mutation of the homogentisate 1,2-dioxygenase (HGD) gene. The HGD gene contains instructions for creating (encoding) an enzyme known as homogentisate 1,2-dioxygenase. This enzyme is essential for the breakdown of homogentisic acid.
What kind of mutation causes alkaptonuria?
What causes Blackbones?
The buildup of acid in the body creates black pigment that attaches to cartilage surrounding the joints. This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations.
Is Alkaptonuria contagious?
Alkaptonuria is inherited, which means it is passed down through families.
What is the history of alkaptonuria?
History Alkaptonuria was one of the four diseases described by Archibald Edward Garrod , as being the result of the accumulation of intermediates due to metabolic deficiencies. He linked ochronosis with the accumulation of alkaptans in 1902, [4] [6] and his views on the subject, including its mode of heritance, were summarized in a 1908 Croonian Lecture at the Royal College of Physicians .
How is alkaptonuria diagnosed?
DIAGNOSIS/TESTING: The diagnosis of alkaptonuria is based on the detection of a significant amount of HGA in the urine by gas chromatography-mass spectrometry analysis. The amount of HGA excreted per day in individuals with alkaptonuria is usually between one and eight grams.
United States. As Garrod suggested, alkaptonuria is an autosomal recessive genetic trait, although an autosomal dominant transmission pattern in 3 generations in a nonconsanguineous family has been reported.The true frequency of alkaptonuria cannot be given with certainty for numerous reasons.
What is the prevalence of alkaptonuria?
Alkaptonuria is a rare disease. According to the National Organization of Rare Disorders (NORD), the exact number of cases is unknown. It is estimated to occur in 1 of every 250,000 -1 million live births in the United States. However, it’s more common in certain areas of Slovakia, Germany, and the Dominican Republic.
