Rod-cone dystrophy of the retina. Continuation of a family study described in 1923

In 1923 Alkio described a sibship with 4 children showing macular dystrophy. In the literature this has been classed among the cone dystrophy group. However, Alkio's patients later became completely blind by the age of 50. According to the hospital records one of them showed marked destruction and pigment degeneration throughout the fundus. The daughter of one of those affected has healthy eyes, but two of her three sons are affected in the same way as their grandfather. They were studied by us in 1987. These two males showed the bull's eye type of macular dystrophy with visual acuity of 20/30 resp 20/50, marked dyschromatopsia, central scotoma in the visual field for weak markers, extinguished ERGs and subnormal EOGs. Dark adaptation was considered pathological especially during the cone phase. The peripheral fundus was within normal limits. The parents of the two patients have a common ancestor born in 1720. Autosomal recessive inheritance is therefore very likely. We think that the disorder is closer to the rod-cone dystrophy group than to cone or cone-rod degenerations.