3-methylglutaconic aciduria type 1 (3-MGA-I) (MIM ID #250950) is an ultra-rare, autosomal recessive organic aciduria, resulting from mutated AUH gene, leading to the deficient 3-methylglutaconyl-CoA hydratase (3-MGH). Only around 40 cases are previously reported, caused by a spectrum of 10 mutations.

The clinical spectrum of 3-MGA-I in children is heterogeneous, varying from asymptomatic individuals to mild neurological impairment, speech delay, quadriplegia, dystonia, choreoathetoid movements, severe encephalopathy, psychomotor retardation, basal ganglia involvement. Early dietary treatment with leucine restriction and carnitine supplementation may be effective in improving neurological state in pediatric patients with 3-MGA-I.

We presented a girl with 3-MGA-I due to novel AUH gene mutation (homozygous variant c.330 + 5G > A) and confirmed by almost undetectable 3-MGH-enzyme activity, who initially presented with central precocious puberty at an early age of 4.5 years.

Precocious puberty might be associated with the 3-MGA-I, as is reported previously in some other metabolic disorders that result in pathologic accumulation of metabolites or toxic brain damage. Therapy with GnRH agonist triptorelin effectively arrested pubertal development.

3-甲基戊二酸尿酸1型（3-MGA-I）（MIM ID＃250950）是一种超罕见的常染色体隐性有机酸尿症，是由AUH基因突变导致的，导致3-甲基戊二酸辅酶A水合酶（3-MGH）不足）。以前仅报道了约40例病例，这些病例是由10种突变引起的。

儿童中3-MGA-I的临床表现各不相同，从无症状个体到轻度神经功能障碍，言语延迟，四肢瘫痪，肌张力障碍，脉络膜动荡，严重脑病，精神运动迟缓，基底神经节受累。限制亮氨酸和肉碱补充的早期饮食治疗可能有效改善3-MGA-I患儿的神经系统状态。

我们介绍了一个因新的AUH基因突变（纯合变异体c.330 + 5G> A）而患有3-MGA-I的女孩，并通过几乎无法检测到的3-MGH酶活性进行了证实，该女孩最初在幼年时就出现了中枢性性早熟为4.5年。

早熟青春期可能与3-MGA-1有关，如先前在其他一些新陈代谢疾病中报道的那样，这些新陈代谢会导致代谢产物的病理性积累或中毒性脑损伤。GnRH激动剂曲普瑞林的治疗有效阻止了青春期发育。