Trace metals in a family with sex-linked retinitis pigmentosa.

Lead, cadmium, copper, and zinc levels were examined in RP patients, carriers, and controls in a family with sex-linked RP. The mean plasma copper concentration was significantly higher in the RP patients and carriers than in the controls. The mean plasma zinc concentration was significantly higher in the carriers than in the RP victims or controls. The mean plasma zinc/copper ratio was significantly lower in the RP victims than in the controls or carriers. These findings may help explain the onset of RP in some sex-linked carriers and may be of diagnostic value.