一例先天性糖基化障碍Ⅱm型患儿的SLC35A2基因变异分析

Analysis of SLC35A2 gene variant in a child with congenital disorder of glycosylation typeⅡm

目的对1例先天性糖基化障碍Ⅱm型(congenital disorder of glycosylation typeⅡm,CDG-Ⅱm)的临床特征及SLC35A2基因变异进行分析,明确其可能的致病原因,为临床诊断提供依据。方法应用全外显子测序对患儿及其父母进行基因变异分析,筛查可疑基因变异进行Sanger验证及相关生物信息学预测分析变异危害性。结果患儿临床表现为癫痫发作、全面发育迟缓、眼球震颤、心肌炎等症状,头颅MRI示两侧额颞部脑沟及蛛网膜下腔较宽等脑发育不良表现,心脏彩超示左心室壁增厚、卵圆孔未闭。基因检测结果显示患儿SLC35A2基因存在c.335C>A(p.Thr112Lys)杂合变异,父母在该位点为野生型,属新发变异,查阅相关文献为未见报道的新变异。根据美国医学遗传学与基因组学学会遗传变异分类标准与指南,SLC35A2基因c.335C>A(p.Thr112Lys)变异判定为可能致病(PS2+PM2+PP3)。结论SLC35A2基因c.335C>A(p.Thr112Lys)变异可能是该例CDG-Ⅱm患儿的致病原因。

Objective To investigate the clinical features andSLC35A2variant of a case of congenital disorder of glycosylation typeⅡm(CDG-Ⅱm),and to identify the possible causes of the disease.Methods Trio-whole exome sequencing(WES)was used to analyze the gene variant of the children and their parents.The suspicious gene variants were screened for Sanger verification and the bioinformatics prediction was used to analyze the hazard of variant.Results The clinical manifestations of the child were epilepsy,global growth retardation,nystagmus,myocarditis and other symptoms.MRI showed brain dysplasia such as wide frontal temporal sulcus and subarachnoid space on both sides.Echocardiography showed left ventricular wall thickening and patent foramen ovale.According to the results of gene detection,there was a heterozygous missense variant c.335C>A(p.Thr112Lys)inSLC35A2 gene.The parents were wild-type at this locus,which was a de novo variant.At the same time,there was no report of this variant in the relevant literature,which was a novel variant inSLC35A2 gene.According to the genetic variant guidelines of American College of Medical Genetics and Genomics,SLC35A2 gene c.335C>A(p.Thr112Lys)variant was predicted to be likely pathogenic(PS2+PM2+PP3).Conclusion The variant ofSLC35A2 gene c.335C>A(p.Thr112Lys)may be the cause of the disease in the child.