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先天性肾上腺增生症(CAH)包括一组不同的遗传性疾病。但本文只述及21-羟化酶缺陷。此酶缺陷约占CAH病人的90%,群体发病率约为1/7000,肾上腺类固醇的21-羟化作用对产生盐皮质激素及糖皮质激素都是必不可少的。无效的21-羟化作用使皮质醇合成减少,使ACTH分泌增多,从而导致肾上腺增生化。ACTH的增多也刺激类固醇前体的合成,在21-羟化作用有缺陷时,可转变为雄性激素,引起子宫内胎儿男性化。21-羟化作用是由细胞色素P450的特殊形式(称为P450 c21)介导的。人类有二种P450 c21基因,称做P450XXI AⅠ和P450XXIAⅡ,这两个基因分别
Congenital adrenal hyperplasia (CAH) includes a group of different genetic diseases. However, this article deals only with 21-hydroxylase deficiency. This enzyme defect accounts for about 90% of patients with CAH, and the incidence of the population is about 1/7000. The 21-hydroxylation of adrenal steroids is essential for the production of mineralocorticoids and glucocorticoids. Ineffective 21-hydroxylation reduces cortisol synthesis and increases secretion of ACTH, leading to adrenal hyperplasia. The increase in ACTH also stimulates the synthesis of steroid precursors. When 21-hydroxylation is defective, it can be converted to androgens, causing uterine fetal masculinization. 21-hydroxylation is mediated by a special form of cytochrome P450 called P450 c21. Humans have two P450 c21 genes called P450XXI AI and P450XXIAII. These two genes are