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枫糖尿病概述

Author
Olaf A Bodamer, MD, PhD, FAAP, FACMG
Section Editor
Sihoun Hahn, MD, PhD
Deputy Editor
Elizabeth TePas, MD, MS
Translators
苟丽娟, 住院医师

引言

枫糖尿病(maple syrup urine disease, MSUD，MIM#248600)也称支链酮酸尿症，是一种影响脂肪族或支链氨基酸的疾病。它是由支链α-酮酸脱氢酶复合物(branched-chain alpha-ketoacid dehydrogenase complex, BCKDC)缺陷导致的，BCKDC是3种支链氨基酸(亮氨酸、异亮氨酸和缬氨酸)代谢通路中的第二种酶。其特征为精神运动发育迟缓、喂养困难及尿有枫糖浆气味。

本文将总结MSUD。氨基酸疾病的一般讨论见其他专题。 (参见“遗传性代谢病：分类”)

流行病学

MSUD在活产婴儿中的发生率为1/185,000-1/86,800[1-3]。在近亲结婚发生率高的群体中发病率更高，如在宾夕法尼亚洲的门诺派教徒中其发生率高达1/200[4]。

病理生理学

支链氨基酸(亮氨酸、异亮氨酸和缬氨酸)是有疏水侧链的必需氨基酸，它们是糖异生、能量产生及脂肪酸和胆固醇合成的重要前体[5]。

在支链代谢的第一个步骤中，支链氨基酸被细胞质和线粒体支链氨基转移酶(branched-chain aminotransferase, BCAT)转变为各自的α-酮酸。之后α-酮酸由BCKDC催化脱羧基，分别产生异戊酰辅酶A(coenzyme A, CoA)、α-甲基丁酰CoA和异丁酰CoA，继而最终生成乙酰CoA、乙酰乙酸和琥珀酰CoA(图 1)[5,6]。

                 

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Literature review current through: 2017-06 . | This topic last updated: 2016-08-16.
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