BACKGROUND Maple syrup urine disease (MSUD) is a potentially life-threatening metabolic disorder caused by decreased activity of the branched-chain α-ketoacid dehydrogenase (BCKD) complex. Mutations in four genes (BCKDHA, BCKDHB, DLD and DBT) are associated with MSUD. Here, the presenting symptoms and clinical course of a case of MSUD with a novel DBT gene mutation are described. CASE PRESENTATION We describe an infant with MSUD with the DBT gene mutation who had drowsiness and poor appetite as well as abnormal findings upon head magnetic resonance imaging (MRI), plasma amino acid analysis and urine organic acid analysis. Genetic testing revealed that both parents had the heterozygous mutation c.1132C > T (p.378X) in chr1:100672078, and the patient had the homozygous mutations c.1132C > T (p.378X) in chr1:100672078. Once diagnosed with MSUD, the patient's disease was controlled with a diet of BCAA-free enteral formula and thiamine. CONCLUSION The mutation c.1132C > T (p.378X) is a novel DBT gene mutation that is associated with MSUD and always has mild clinical manifestations. After timely BCAA-free nutrition and supplementation with thiamine for the patient, the plasma levels of BCAAs reached a safe level, the abnormal range of the multiple intracranial abnormalities was significantly smaller than before, and the symptoms of drowsiness and poor appetite disappeared.

中文翻译：

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病例报告：具有新型DBT基因突变的枫糖浆尿病。

背景技术枫糖浆尿病（MSUD）是由支链α-酮酸脱氢酶（BCKD）复合物的活性降低引起的潜在的危及生命的代谢疾病。四个基因（BCKDHA，BCKDHB，DLD和DBT）的突变与MSUD相关。在此，描述具有新型DBT基因突变的MSUD病例的表现症状和临床过程。病例介绍我们描述了一个患有DBT基因突变的MSUD婴儿，该婴儿嗜睡，食欲不振以及头部磁共振成像（MRI），血浆氨基酸分析和尿液有机酸分析异常。遗传测试显示，父母双方在chr1：100672078中均具有杂合突变c.1132C> T（p.378X），并且患者在chr1：100672078中均具有c.1132C> T（p.378X）纯合突变。一旦诊断出MSUD，用不含BCAA的肠溶配方和硫胺素饮食控制患者的疾病。结论突变c.1132C> T（p.378X）是一种新的DBT基因突变，与MSUD相关，并且始终具有轻度的临床表现。经过及时的无BCAA营养补充硫胺素后，患者血浆BCAAs达到安全水平，多种颅内异常的异常范围明显小于以前，嗜睡和食欲不振的症状消失了。