SPERM ABNORMALITIES IN RETINITIS-PIGMENTOSA

Purpose. To determine the fatty acid composition of erythrocytes and s perm, along with the functional characteristics of sperm, in patients with retinitis pigmentosa. Sperm and retinal cells share important hom ologies. Both are rich in the highly polyunsaturated fatty acid, docos ahexaenoic acid (DHA, 22:6[n-3]), and both contain a structural compon ent called the axoneme. Low concentrations of DHA in the retina of mon keys are known to cause visual impairment. Because blood levels of DHA in retinitis pigmentosa patients are less than normal, reduced DHA in the retina might contribute to the visual impairment characteristic o f this disease. This study was conducted on the hypothesis that the sp erm of retinitis pigmentosa patients might be abnormal and that these abnormalities might infer similar lipid and structural abnormalities o f the retina. Methods. The lipid composition of erythrocytes and sperm (fatty acids and sterols) and sperm function were analyzed in 26 pati ents with retinitis pigmentosa and in 8 healthy men. Results. The sper m of patients with retinitis pigmentosa had a much lower DHA concentra tion, a lower desmosterol-to-cholesterol ratio, reduced motility, abno rmal structure, and lower sperm counts compared with that in normal su bjects. Usher's II patients exhibited the most pronounced reductions o f DHA in sperm. Sperm DHA concentration was positively correlated to s perm motility, to sperm count, and to the desmosterol-to-cholesterol r atio. Lower erythrocyte DHA was also observed in retinitis pigmentosa patients. Conclusions. These results indicate that the sperm of patien ts with retinitis pigmentosa, particularly those with Usher's II, have an abnormal lipid composition that is associated with reduced motilit y. The possibility exists that these patients might have similar abnor malities in the DHA biochemistry of the retina, Sperm biochemistry and function may be a marker for this disease. A clinical trial of DHA in retinitis pigmentosa is suggested for future study.