Search

SummaryThe different varieties of congenital dyschromatopsias are inherited following different modes. The dyschromatopsias of the protan and deutan type, as well as the atypical achromatopsia (blue mono-cone monochromacy), are sex-linked recessive, the tritanopia probably autosomal dominant and the typical achromatopsia surely autosomal recessive. The mode of transmission of the tritanomalia is still dubious.Concerning the localisation of the genes on the X chromosome, the bilocular theory for the deutan and protan genes is accepted at the present time. These genes form a cluster with the genes of hemophilia A and G6PD deficiency. It is possible that this cluster is situated on the short arm of the X chromosome or on the long arm near the centromeric region. The exact situation will be known very soon, when the interpretation of the results of the cellular hybridisation, which are still discordant, will be well established.

In 1960, Alpern, Falls, and Lee reviewed the extensive literature on congenital monochromatism and then described the visual characteristics of five patients with typical total monochromacy.1At the time these data were presented, one of us (H.F.F.) made a plea for eyes of this kind which might become available for histological examination. One such case has now been described, but the eyes were only obtained 40 hours after death, at which time considerable autolysis of the photoreceptor layer had already occurred.2In the case to be presented, the eye was fixed immediately after surgical enucleation. While we had no psychophysical measurements on this observer at that time, we have since obtained good measurements of the color vision and dark adaptation characteristics of her remaining eye. The present paper will describe the results of both the histological examination and the psychophysical measurements. Report of Case A 69-year-old white woman