What is the primary outcome of alkaptonuria?

• A. Buildup of phenylalanine
• B. Buildup of acid
• C. Deficiency of methionine
• D. Excess uric acid in urine

Answer: (B)

The primary outcome of alkaptonuria is indeed the buildup of acid, specifically homogentisic acid. This rare genetic condition results from a deficiency of the enzyme homogentisate oxidase, which is involved in the metabolic pathway that breaks down the amino acids phenylalanine and tyrosine. When this enzyme is deficient, homogentisic acid accumulates in the body, leading to various complications including darkening of the urine, arthritis, and potential heart issues.

The incorrect options relate to different metabolic disorders. The buildup of phenylalanine is characteristic of phenylketonuria, not alkaptonuria. A deficiency of methionine does not relate to alkaptonuria, as this condition specifically involves the metabolism of tyrosine and phenylalanine. Excess uric acid in urine is primarily associated with disorders like gout or certain types of kidney disease, rather than with alkaptonuria, which revolves around the accumulation of homogentisic acid.