The Familial Distribution of Congenital Tritanopia

Summary Tritanopia was studied in forty‐seven affected individuals. Of these twenty‐two are propositi and twenty‐five relatives of propositi. The various tests used for the diagnosis of tritanopia are described and their efficiency is discussed. The familial incidence suggests that the bulk of congenital tritanopia is due to one or several autosomal dominant genes, with somewhat imperfect manifestation. On a single‐gene hypothesis, the incidence of the gene in England is estimated at about 1 in 20,000.