甲基丙二酸尿症又称甲基丙二酸血症,是一种常见的遗传代谢性疾病,主要分为8种亚型,即变位酶蛋白缺陷的两种亚型和维生素B12代谢缺陷的6种亚型,其中cbl C、cbl D和cbl F在临床上表现为甲基丙二酸尿症合并同型半胱氨酸血症。本文报道1例以精神行为异常为首发表现的甲基丙二酸尿症合并同型半胱氨酸血症患儿资料,以期提醒临床医师对于有精神行为异常表现的患儿注意 Methylmalonic aciduria, also known as methylmalonic acidemia, is a common inherited metabolic disease that is divided into eight subtypes, namely, two subtypes of the mutated enzyme deficiency and vitamin B12 metabolism Six subtypes of defects, of which cbl C, cbl D and cbl F are clinically manifested as methylmalonic aciduria with homocysteinemia. This article reports a case of mental behavioral abnormalities as the first manifestation of methylmalonic acid in children with homocysteinemia data to remind clinicians for mental disorders in children with abnormal performance