Slide showing pedigree chart of 'Alkaptonuria'. Slide shows black and white pedigree chart of 'Alkaptonuria'. Title under slide image reads 'Fig. 4 Pedigree of Alkaptonuria, showing consanguinity. Key - [black spot enclosed in square] and [black spot enclosed in circle]= hetrozygous. [Square with diagonal line through] and [circle with diagonal line through] = died in infancy.' Alkaptonuria is a genetic disease in which the body does not have enough of the homogentisic acid oxidase (HGAO) enzyme. Late 19th - early 20th century