A 9-day-old male patient was admitted to the hospital because of cough, anhelation, feeding difficulty and lethargy. The diagnostic examinations indicated pulmonary infection, severe metabolic acidosis, hyperglycemia, hyperammonemia and pancytopenia in the patient. Blood and urine screening and isovaleryl-CoA dehydrogenase (IVD) gene detection for inherited metabolic diseases were performed to clarify the etiology. Tandem mass spectrometric screening for blood showed an elevated isovalerylcarnitine (C5) level. The organic acid analysis of urine by gas chromatography-mass spectrometry showed significantly increased levels in isovaleryl glycine and 3-hydroxyisovaleric acid. Homozygous mutations (c.1208A>G, p.Tyr403Cys) in the IVD gene were identified in the patient. His parents were heterozygous carriers. After the treatment with low-leucine diets and L-carnitine for 3 days, the patient showed a significant improvement in symptoms, but he died one week later. It is concluded that the neonates with pneumonia and metabolic decompensation of unknown etiology should be screened for genetic metabolic disease.
患儿，男，9d，急性起病，表现为咳嗽、气促、喂养困难、嗜睡、昏迷。辅助检查提示肺部感染、严重代谢性酸中毒、高血糖、高血氨、血象三系减少。为查明病因，进行了血液酯酰肉碱谱及尿液有机酸分析及基因诊断。结果发现：血异戊酰肉碱及尿异戊酰甘氨酸和3-羟基异戊酸显著升高，游离肉碱降低，提示异戊酸血症（IVA）；基因检测提示第12号外显子纯合突变c.1208A > G（p.Tyr403Cys），父母为杂合突变携带者。经低亮氨酸饮食、左卡尼汀等治疗后症状稍改善，但1周后患儿死亡。新生儿肺炎是新生儿常见感染，但可能是遗传代谢病患儿的诱发因素，因此对于肺炎起病的伴有难以解释的代谢异常患儿，应进行遗传代谢性疾病筛查。