Wetzel M G, Fahlman C, Maude M B, Alvarez R A, O'Brien P J, Acland G M, Aguirre G D, Anderson R E
National Eye Institute, Bethesda, MD.
Prog Clin Biol Res. 1989;314:427-39.
It is possible that a genetic defect observed in the prcd poodle involves the abnormality of an enzyme which functions in phospholipid or lipoprotein metabolism. In our studies thus far, we have been unable to detect any defect in retinal phospholipid biosynthesis, but we have noted a decrease in plasma levels of 22:6w3 which may be a result of an enzyme defect in liver biosynthesis of 22:6w3 from its dietary precursor, linolenic acid, or some defect in the blood lipoprotein transport of this essential fatty acid. If 22:6w3 is essential to the normal elaboration and functioning of the photoreceptor outer segment, it is possible that decreased access to this fatty acid due to lower blood levels of 22:6w3 could cause photoreceptor abnormalities. Further studies are needed to confirm the possible defect in delta-4 desaturase activity and possible dietary modification of the course of this prcd retinal degeneration.
在进行性视网膜萎缩（prcd）贵宾犬中观察到的基因缺陷，可能涉及一种在磷脂或脂蛋白代谢中起作用的酶的异常。在我们目前的研究中，我们未能检测到视网膜磷脂生物合成中的任何缺陷，但我们注意到血浆中22:6w3水平降低，这可能是由于肝脏从其膳食前体亚麻酸生物合成22:6w3时的酶缺陷，或者是这种必需脂肪酸在血液脂蛋白运输中的某些缺陷所致。如果22:6w3对光感受器外段的正常形成和功能至关重要，那么由于血液中22:6w3水平降低导致该脂肪酸的可利用性降低，可能会导致光感受器异常。需要进一步的研究来证实δ-4去饱和酶活性可能存在的缺陷，以及对这种prcd视网膜变性病程进行可能的饮食调整。
