The genetics of tritan disturbances

Summary Tritan (blue-green) colour vision disturbances have been found in 79 individuals in six families, revealing an autosomal dominant mode of inheritance with a wide variability of test results within families. Evidence is presented that it is—in contradistinction to the X-chromosomally inherited redgreen defects—incorrect to make a subdivision between dicromasia (tritanopia) and anomalous trichromasia (tritanomaly). On the basis of three small screening series, totalling 1900 individuals, the frequency of tritan disturbances in estimated to be around 2 per 1000. Seven males have been observed carrying both inherited tritan and red-green defects.