Alkaptonuria is a rare inherited disorder that is transmitted in an autosomal recessive pattern. This means that both copies of the gene responsible for alkaptonuria must be mutated or altered for a person to have the condition.
The specific gene associated with alkaptonuria is called the HGD gene, which provides instructions for producing an enzyme called homogentisate 1,2-dioxygenase. This enzyme is involved in the breakdown of an amino acid called phenylalanine and a related compound called tyrosine. Mutations in the HGD gene result in a deficiency or complete absence of this enzyme.
When both parents are carriers of a single mutated copy of the HGD gene, there is a 25% chance in each pregnancy for the child to inherit two mutated copies and have alkaptonuria. The chance of inheriting a single mutated copy and becoming a carrier like the parents is 50%. The remaining 25% chance is for the child to inherit two normal copies of the gene and not be affected by the condition.
It’s important to note that carriers of a single mutated copy of the HGD gene typically do not exhibit symptoms of alkaptonuria, as the condition requires two mutated copies to manifest. However, carriers can pass on the mutated gene to their children.
