Question

Alkaptonuria is ______ disorder.

• A. Sex linked dominant
• B. Sex linked recessive
• C. Autosomal recessive
• D. Autosomal dominant

Answer 1

The correct option is C Autosomal recessive

The genes for sex linked dominant traits are present on sex chromosomes. The sex linked dominant traits can expresse themselves in both heterozygous and homozygous conditions. The sex linked recessive traits can express themselves in homozygous conditions only. Alkaptonuria is an inborn metabolic error marked by inability of body to process the amino acids phenylalanine and tyrosine. A mutation in the HGD gene, that codes for the enzyme homogentisate 1,2-dioxygenase, is responsible for this disorder. This gene is present on the autosome, hence, it is an autosomal disorder whose inheritance is independent on the sex of the person. The mutated allele can express itself in homozygous conditions only, thus, the trait is not dominant; it is a recessive condition.