Pathophysiological investigation on cerebrotendinous xanthomatosis

脑腱黄瘤病是一种代谢性疾病，以神经功能障碍、腱黄瘤和幼年白内障为特征。由于肝酶的缺陷，CTX患者将胆固醇转化为胆汁酸的能力受损，肝酶可以催化甾醇中间体侧链的氧化。1969年柴崎报告了日本的第一例病例。我们的目的首先是明确CTX患者的基因突变，其次是建立CTX疾病的实验模型动物。CTX患者的遗传异常：我们（Seyama, Yonemoto， Hoshita和Kubota）与Ingemar Bjoerkhem合作，分析了编码甾醇27-羟化酶的cDNA的核苷酸序列。RT-PCR产物的直接测序显示，在5例CTX患者中，血红素配体结合位点发生突变。在第441位的精氨酸被谷氨酰胺或色氨酸取代，在编码第445个氨基酸的位置也发现了一个碱基缺失。在以谷氨酰胺替代精氨酸的患者中，出现了一个新的限制性酶切位点“Stu 1”。在用色氨酸替代精氨酸的患者中，“Hpa II”位点消失。这些发现提示使用RFLP.2进行遗传诊断的可能性。CTX实验模型动物的建立：我们（Seyama和Kasama）与Salen和sherfer合作，通过饲喂胆固醇日粮建立了CTX实验模型动物。在饲粮中添加1%的胆固醇后，20%的小鼠出现胆结石，并伴有胆囊黏膜炎症和浆膜血管壁增厚。肝脏HMG-CoA还原酶活性升高51%，而胆固醇7a-羟化酶活性严重降低。停用饮食中的胆固醇1个月后，升高的血清和肝脏胆固醇浓度降低，肝脏HMG-CoA还原酶和胆固醇7a-羟化酶恢复正常。胆固醇合成增加与胆汁酸形成减少的结合促进了胆固醇喂养小鼠胆石的形成。少

Cerebrotendinous xanthomatosis is a metabolic disease, characterized by neurologic dysfunction, tendon xanthomas and juvenile cataracts. CTX patients have an impaired capacity to convert cholesterol to bile acids, due to a defect of hepatic enzyme, which catalyzes the oxidation of side chains of sterol intermediates. The first case in Japan was reported by Shibasaki in 1969.We intended first to clarify the genetic mutations in CTX patients, and secondly to establish an experimental model animal of this disease.1. Genetic abnormalities in CTX patients : In collaboration with Ingemar Bjoerkhem, we (Seyama, Yonemoto, Hoshita and Kubota) analyzed the nucleotide sequence of cDNA encoding the sterol 27-hydroxylase. Direct sequencing of RT-PCR products revealed a mutation at the heme-ligand binding site in five CTX patients. Arginine at the 441 position was replaced by glutamine or tryptophan, and one base deletion was also found in one patient at the position encoding 445th amino acid. In pa … More tients with replacement of arginine by glutamine, a new restriction site with "Stu I" appeared. In patients with a replacement of arginine by tryptophan, "Hpa II" site disappeared. These findings suggest a possibility of genetic diagnosis using RFLP.2. Establishment of experimental model animal of CTX : In collaboration with Salen and Shefer, we (Seyama and Kasama) established an experimental model animal by feeding cholestanol diet. After feeding 1% cholestanol in the diet, gallstones developed in 20 % of the mice and were associated with gallbladder mucosal inflammation and serosal vessel wall thickening. Hepatic HMG-CoA reductase activity rose by 51 % In contrast cholesterol 7a-hydroxylase activity was severely depressed. Discontinuing cholestanol from the diet for 1 month, reduced the elevated serum and liver cholestanol concentrations, and restored hepatic HMG-CoA reductase and cholesterol 7a-hydroxylase to normal. The combination of increased cholesterol synthesis with decreased bile acid formation promotes gallstone formation in cholestanol fed mice. Less