肉碱棕榈酰转移酶Ⅱ缺乏症家系CPT2基因突变分析及产前诊断

CPT2 gene mutation analysis and prenatal diagnosis in a family with carnitine palmitoyltransferase II deficiency

摘要:

分析肉碱棕榈酰转移酶Ⅱ（CPTⅡ）缺乏症患儿及其父母CPT2基因突变类型，为家系成员提供遗传咨询及产前诊断。先证者，女，于3个月时发烧8 h入院，血液酯酰肉碱谱分析显示棕榈酰肉碱显著增高，提示CPTⅡ缺乏症。收集患儿临床资料，采集患儿和父母外周血，提取基因组DNA，应用直接测序法进行CPT2基因5个外显子编码区及与外显子交界的部分内含子区域进行测序。患儿母亲于妊娠中期采取羊水，分取羊水细胞进行CPT2基因突变分析。Sanger测序发现先证者CPT2基因存在两个已知致病突变c.886C > T（p.R296X）和c.1148T > A（p.F383Y），突变来自父母双方。母亲第二胎羊水细胞CPT2基因存在c.886C > T（p.R296X），为致病基因携带者。胎儿出生后血液酯酰肉碱谱正常，发育正常。通过家系CPT2基因分析，证实了先证者死因为CPTⅡ缺乏症，在突变明确的前提下，成功地进行了下一胎同胞的产前诊断，为该家庭提供帮助。

Abstract:

This study aimed to identify the type of carnitine palmitoyltransferase 2 (CPT2) gene mutation in the child with carnitine palmitoyltransferase II (CPT II) deficiency and her parents and to provide the genetic counseling and prenatal diagnosis for the family members. As the proband, a 3-month-old female baby was admitted to the hospital due to fever which had lasted for 8 hours. Tandem mass spectrometric analysis for blood showed an elevated plasma level of acylcarnitine, which suggested CPT II deficiency. The genomic DNA was extracted from peripheral blood of the patient and her parents. Five exon coding regions and some intron regions at the exon/intron boundaries of the CPT2 gene were analyzed by PCR and Sanger sequencing. Amniotic fluid was taken from the mother during the second trimester, and DNA was extracted to analyze the type of CPT2 gene mutation. Sanger sequencing results showed that two mutations were identified in the CPT2 gene of the proband:c.886C > T (p.R296X) and c.1148T > A (p.F383Y), which were inherited from the parents; the second child of the mother inherited the mutation of c.886C > T (p.R296X) and showed normal acylcarnitine spectrum and normal development after birth. It is concluded that the analysis of CPT2 gene mutations in the family suggested that the proband died of CPT II deficiency and that the identification of the mutations was helpful in prenatal diagnosis in the second pregnancy.