Electro-rentinal abnormalities in heterozygotes of renal-retinal dysplasia.

The relatives of two patients with medullary cystic disease associated with retinitis pigmentosa were studied. A new case was found in one of these families, and consanguinity of the parents was established in another. Conventional fundoscopic examination of relatives without renal disease did not show retinal abnormalities, but electro-ophthalmologic investigation demonstrated retinal dysfunction in three relatives, including two of the four parents who may be considered obligatory heterozygotes under the assumption of autosomal recessive inheritance of this syndrome. Less severe electro-ophthalmological abnormalities were observed in the other two parents. It is considered highly probable that all three patients are homozygous for a mutant gene causing both the renal and the retinal abnormalities. The results of this study support the view that medullary cystic disease associated with retinitis pigmentosa is transmitted as an autosomal recessive trait, in contrast to the dominant form, which is reported not to be associated with eye abnormalities. With respect to genetic couseling and donation of kidneys by relatives, it is important to establish the mode of inheritance of cystic medullary disease in a given family. Electro-ophthalmologic examination should therefore be included in the examination of families in which medullary cystic disease occurs.