What is the Difference Between Alkaptonuria and Phenylketonuria?

Alkaptonuria and phenylketonuria are two distinct inborn errors of metabolism, which are rare inherited genetic disorders caused by defects in specific enzymes. The key difference between the two is the amino acids they affect and the resulting symptoms.

Alkaptonuria:

• Inability to metabolize two amino acids, tyrosine and phenylalanine.
• Results in increased levels of homogentisic (or melanic) acid.
• Causes dark brown pigmentation of the permanent teeth, urine discoloration, and cartilage pigmentation.
• Symptoms typically develop in people over 30 years old.
• Global prevalence is 1 in 250,000 to 1,000,000 live births.

Phenylketonuria:

• Inability to metabolize the amino acid phenylalanine.
• Causes intellectual disability, seizures, behavioral problems, and mental disorders.
• Results in lighter skin and a musty smell.
• Main cause is a mutation in the PAH gene, which encodes for the nonfunctional phenylalanine hydroxylase.
• Global prevalence is 1 in 23,930 live births.

In summary, alkaptonuria and phenylketonuria are two different inborn errors of metabolism that affect the metabolism of amino acids. Alkaptonuria results from the inability to metabolize tyrosine and phenylalanine, causing increased levels of homogentisic acid and various symptoms. On the other hand, phenylketonuria is characterized by the inability to metabolize phenylalanine, leading to a range of health issues and a distinct set of symptoms.

Comparative Table: Alkaptonuria vs Phenylketonuria

Alkaptonuria and phenylketonuria are both inborn errors of metabolism, which are rare inherited genetic disorders that affect the body's ability to properly turn food into energy. Here is a table comparing the differences and similarities between the two disorders:

Both disorders are inherited in an autosomal recessive manner, meaning that an individual must inherit two mutated copies of the gene (one from each parent) to develop the disorder.