Genetic approach to Wilson disease by use of the hereditary hepatitis LEC rats

LEC大鼠在出生后约4个月突然发育。大约30%的大鼠在1周内死于暴发性肝炎，其余的存活于慢性肝炎，随后发展为肝癌。近来发现LEC大鼠肝脏铜蓄积量高，血清铜蓝蛋白明显降低，这些临床和生化特征与Wilson病非常相似，因此我们提出LEC作为Wilson病的动物模型。我们将hts定义为肝炎的基因标志。本研究利用回交大鼠检测Wilson病基因WNE与hts是否同源：（1）LEC回交大鼠的遗传分析表明hts与ESD基因、RB1基因以及与人WND连锁的几个小卫星DNA均不连锁，表明hts与RB1和ESD基因位于不同的15号染色体上。(2)由于LEC大鼠血清铜蓝蛋白明显降低，我们从LEC中分离出铜蓝蛋白基因，未发现LEC中铜蓝蛋白基因的突变，提示铜蓄积不是由于铜蓝蛋白基因的改变所致。Wilson病的hts和WND的连锁分析显示了相同的分离模式，没有重组，证明WND基因是hts的主要候选基因。本文结果提示LEC大鼠肝炎可能是由铜转运ATP酶缺陷引起的，可能是由于hts突变所致。

LEC rats develop abruptly about 4months after birth. Abot 30% of the rats die of fulminant hepatitis within 1 week, and remainder survive with chronic hepatitis and subsequently develop liver cancer. Recently, high levels of copper accumulation in the livers of LEC rats and gross reduction of serum ceruloplasmin have been found. These clinical and biochemical characteristics of LEC rats are very similar to Wilson disease, and therefore, we proposed the LEC as an animal model for Wilson disease. We defined hts as the gene symbol for the hepatitis. In this research project, we have examined whether the gene, WNE, for Wilson disease is homologous to the hts by use of backcross rats :(1) Genetic analysis by use of backcross rats of LEC showed no linkage between hts and genes for ESD, RB1, and several minisatellite DNAs which linked to the WND in human, indicating that the hts locates on a different chromosome from no.15 on which RB1 and ESD are located.(2) As gross reductin of serum ceruloplasmin was found in LEC rats, we have isolated the gene for ceruloplasmin from the LEC, and found no mutation in the gene of LEC, suggesting that the copper accumulatino is not due to alteration of the ceruloplasmin gene.Linkage analysis of the hts and WND for Wilson disease showed the identical segregation pattern and no recombination demonstrating that the WND gene is a prime candidate for hts.Thus, the results obtained here suggest that the hepatitis of LEC rats may be caused by a defect in a copper transporting ATPase, possibly due to mutation of hts.