Colour vision in a family with Sorsby's dystrophy

Abstract

Fraser & Wallace (1971) investigated a family with Sorsby’s dystrophy, and found a high prevalence of a mild red-green colour deficiency. Using a battery of tests, I re-examined the colour vision of members of the family at risk of developing the disease. I concluded that the mild colour vision defect is classical sex linked recessive deuteranomaly occurring adventiously in the family; its high prevalence is due to its being introduced by at least 3 persons marrying into the family. Two alternative hypotheses of the colour vision deficiency are that it is an acquired disorder which is a prodromal sign of the dystrophy or that it is inherited in an autosomal dominant manner. However, these hypotheses were rejected because the colour vision deficiency had the characteristics of a typical sex linked disorder. These findings emphasise that it is important to exclude any co-existing inherited colour vision defect when defining the clinical features of any retinal dystrophy by careful evaluation of unaffected family members.