In particular, Alkaptonuria (AKU) is an ultra-rare autosomal recessive metabolic disease [3] with a very low prevalence (1:1,000,000–250,000) [4], caused by mutation in the structure of homogentisate 1,2-dioxygenase (HGD) [4], an enzyme involved in the metabolism of tyrosine and phenylalanine. The gene discussed is HGD; the disease is alkaptonuria.