Subsequent genetic analysis of the I HGD i gene (encoding homogentisate 1, 2 di-oxygenase) identified a homozygous missense pathogenic mutation in exon 6, c.365C>T ( B p.Ala122Val b ) confirming a diagnosis of alkaptonuria. Further biochemical evaluation revealed an elevated urinary homogentisic acid (HGA) 642.36 (Normal Range <1%). Alkaptonuria is an autosomal recessive condition with impaired tyrosine metabolism due to mutations in the I HGD i gene, which results in the accumulation of HGA.