串联质谱法检测结果阴性的甲基丙二酸血症合并同型半胱氨酸血症cblX型患儿一例

A case of methylmalonic acidemia and homocysteinemia cblX type with negative tandem mass spectrometry testing

一例甲基丙二酸血症合并同型半胱氨酸血症cblX型患儿在婴儿早期出现局灶性癫痫发作和癫痫性痉挛发作,多种抗癫痫药物治疗效果不佳,患儿于4月龄时死亡。新生儿筛查和急性发作期串联质谱法检测均未见明显异常,超高效液相色谱-串联质谱法检测提示血甲基丙二酸和同型半胱氨酸增高,全外显子组测序显示HCFC1基因存在c.202C>G(p.Q68E)半合子突变,遗传自其母亲。

A child with methylmalonic acidemia and homocysteinemia cblX type presented focal seizures and epileptic spasms in early infancy, but the tandem mass spectrometry tests showed negative results during neonatal screening or acute attack.Despite treated with a variety of antiepileptic drugs, the child died at age of 4 months. The blood spot sample of the patient was retrospectively tested with ultrahigh performance liquid chromatography-tandem mass spectrometry, and the increased levels of methylmalonic acid and homocysteine were revealed. Whole exome sequencing showed that the proband had a c.202 C>G(p.Q68 E) hemizygous mutation inHCFC1 gene, which was inherited from his mother.