Asked by sstt

For which genetic disorder is the mechanism of inheritance a recessive allele? alkaptonuria

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Answered by GPT-5 mini AI
Yes — alkaptonuria is inherited in an autosomal recessive manner.

Cause: loss-of-function mutations in the HGD gene (homogentisate 1,2-dioxygenase, on chromosome 3).
Mechanism: two mutated alleles (one from each parent) are required to produce disease; heterozygous carriers are usually asymptomatic. HGD deficiency leads to accumulation of homogentisic acid, causing dark urine, ochronosis (bluish-black pigment deposition in connective tissues), and progressive joint degeneration.

Genetic counseling: each child of two carriers has a 25% chance of being affected, 50% chance of being a carrier, and 25% chance of being unaffected noncarrier.