Question

In a research article about Alkaptonuria published in 1902, Garrod suggested that humans inherit two "characters" (alleles) for a particular enzyme and that both parents must contribute a faulty version for the offspring to have Alkaptonuria. Today, would this disorder be called dominant or recessive?

Short answer

Alkaptonuria is a metabolic defect that causes the accumulation of the homogenistic acid in the body, a type of phenolic acid. It is a recessive condition that affects the offspring.

Step-by-step solution

Definition of alleles

The variant form that is present within the gene is known as an allele. There are types of alleles, such as dominant allele and recessive allele.

The dominant allele can affect the offspring that has one copy of the allele. The recessive allele can affect the individual if inherited from both parents.

Enzyme involved in Alkaptonuria

The enzyme responsible for this condition is homogentisate 1, 2-dioxygenase. The deficiency of this enzyme leads to the accumulation of homogentisic acid in the body. This acid is a product of phenylalanine and tyrosine metabolism.

Alkaptonuria is a recessive condition

The alleles coding for the enzymehomogentisate 1, 2-dioxygenase is defective. The alleles transferred from both the parents are defective in this condition. It results in the inheritance of alkaptonuria.

The alkaptonuria condition occurs when both the alleles are defective inthis state. It is a recessive condition because it involves two copies of the allele to inherit the disorder to the offspring.

Hence, alkaptonuria is a recessive condition that occurs when both the parents transfer the faulty allele to the offspring.