Analysis of a Chinese pedigree affected with Spinal muscular atrophy due to compound heterozygous variants ofSMN gene
古艳 1李丽萍 1陈辉 2徐灵均 2方颖慧 1徐细花 1龙颖颖 3李岭
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作者信息
1. 1南昌市第一医院，南昌 330006
2. 3江西省儿童医院，南昌 330006
3. 2南昌大学第二附属医院，南昌 330006
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摘要
目的 分析1个脊髓性肌肉萎缩症(SMA)家系SMN1基因的变异情况，为遗传咨询和产前诊断提供依据。 方法 以2020年1月在南昌市第一医院就诊的1个SMA家系作为研究对象。采集其外周血样，提取DNA，用多重连接探针杂交(MLPA)法对患儿及其亲属的SMN基因进行检测，再用二代测序(NGS)对患儿进行变异分析，用Sanger测序法对结果进行验证。同时采集外周血样，提取cDNA，以先证者cDNA为模板甄别点变异在SMN1和SMN2基因中的分布情况。 结果 先证者的SMN1基因存在Exon7+Exon8杂合缺失及c.81G>A复合杂合变异，其中c.81G>A变异遗传自其母亲及外祖，SMN1 Exon7+Exon8杂合缺失遗传自父亲及祖母。其姨妈携带SMN1 c．81G>A杂合缺失，姑姑、姑父及表妹未检测到外显子缺失。通过cDNA扩增和Sanger测序，明确c.81G>A变异位于SMN1基因。 结论 MLPA联合Sanger测序、NGS技术能够明确SMA患者携带的SMN基因的复合杂合变异。 Objective To analyze variants of SMN gene in a Chinese pedigree affected with Spinal muscular atrophy (SMA). Methods A Chinese pedigree diagnosed at the Nanchang First Hospital in January 2020 was selected as the study subject. Peripheral blood samples were collected for the extraction of DNA. All exons of the SMN gene were detected by multiple ligation-dependent probe amplification (MLPA). Potential variants of the SMN gene were also detected by Whole exome sequencing (WES), and the result was verified by Sanger sequencing. cDNA extracted from fresh blood sample was used as a template to verify the location of variant on the SMN genes. Results The proband was found to harbor a heterozygous deletion of the SMN1 Exon7+ Exon8, and a heterozygous c. 81G>A variant. TheSMN1 Exon7+ Exon8 deletion was inherited from her father and grandmother, whilst the c. 81G>A variant was inherited from her mother and maternal grandfather. Her aunt was also a carrier of the heterozygous deletion, while her paternal aunt, her husband, and their daughter were not. cDNA amplification and Sanger sequencing confirmed that the c. 81G>A variant was located in theSMN1 gene. Conclusion MLPA combined with NGS and Sanger sequencing can identify compound heterozygous variants of the SMN gene in the SMA patients.
Abstract
Objective To analyze variants of SMN gene in a Chinese pedigree affected with Spinal muscular atrophy (SMA). Methods A Chinese pedigree diagnosed at the Nanchang First Hospital in January 2020 was selected as the study subject. Peripheral blood samples were collected for the extraction of DNA. All exons of the SMN gene were detected by multiple ligation-dependent probe amplification (MLPA). Potential variants of the SMN gene were also detected by Whole exome sequencing (WES), and the result was verified by Sanger sequencing. cDNA extracted from fresh blood sample was used as a template to verify the location of variant on the SMN genes. Results The proband was found to harbor a heterozygous deletion of the SMN1 Exon7+ Exon8, and a heterozygous c. 81G>A variant. TheSMN1 Exon7+ Exon8 deletion was inherited from her father and grandmother, whilst the c. 81G>A variant was inherited from her mother and maternal grandfather. Her aunt was also a carrier of the heterozygous deletion, while her paternal aunt, her husband, and their daughter were not. cDNA amplification and Sanger sequencing confirmed that the c. 81G>A variant was located in theSMN1 gene. Conclusion MLPA combined with NGS and Sanger sequencing can identify compound heterozygous variants of the SMN gene in the SMA patients.
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