This is a pedigree for a family with a history of alkaptonuria, a rare metabolic disorder in which patients cannot breakdown homogenistic acid. This may result in urine that turns black when exposed to air. These individuals develop a bluish-black discoloration of connective tissues, discoloration of the skin, progressive arthritis, and other symptoms. What type of inheritance is this and what is the evidence? The shaded (striped) circles or squares means that the individual has the characteristic. Prepared by Olga R. Kopp Autosomal recessive. Meredith and J.C. don't have the disorder but their son does (individual III 4) Epistasis because one gene affects many characteristics. Sex-linked. Tina passed it to her son Peter and to her daughter J.R. Autosomal dominant. It is present in all generations.