UNASSIGNED: Whole exome sequencing was performed for 4 unrelated CHD families with extracardiac malformations, candidate genes were screened by using stringent bioinformatics analysis, and the obtained variants were confirmed by Sanger sequencing. RT-PCR and Sanger sequencing were used to investigate the influence of a splice variant on pre-mRNA splicing. Further targeted sequencing was conducted to investigate the association of CHD7 variants with sporadic CHD.
UNASSIGNED: Four novel heterozygous loss-of-function CHD7 mutations were found by using stringent bioinformatics analysis: the frameshift mutation c.1951_1952delAAinsT (p.L651X) in family #1, the nonsense mutations c.2913C>G (p.Y971X) in family #2 and c.3106C>T (pA1036X) in family #3, and the splicing mutation c.4353+4_4353+12delinsGCCCA in family #4. Sanger sequencing confirmed that these were all de novo mutations and were absent in the healthy parents and siblings of the probands. Further studies revealed that the splice mutation c.4353+4_4353+12delinsGCCCA influenced CHD7 mRNA splicing in vivo. Targeted sequencing found 23 rare mutations in 1,155 sporadic CHD patients.
UNASSIGNED: The findings here confirm that de novo loss-of-function variants of the CHD7 gene are the genetic cause of familial CHD with extracardiac malformations and the spectrum of pathogenic CHD7 variants in sporadic CHD is expanded.
■对4个心外畸形无关CHD家族进行全外显子组测序,通过严格的生物信息学分析筛选候选基因,并通过Sanger测序确认获得的变体。使用RT-PCR和Sanger测序来研究剪接变体对前mRNA剪接的影响。进行进一步的靶向测序以研究CHD7变体与散发性CHD的关联。
■通过使用严格的生物信息学分析发现了四个新的杂合功能丧失CHD7突变:移码突变c.1951_1952delAAinsT(p。L651X)在1号家族中,无义突变c.2913C>G(p。Y971X)在家族#2中,c.3106C>T(pA1036X)在家族#3中,剪接突变c.43534_435312delinsGCCCA在家族#4中。Sanger测序证实,这些都是从头突变,在先证者的健康父母和兄弟姐妹中不存在。进一步的研究表明,剪接突变c.4353+4_4353+12delinsGCCCA影响了体内CHD7mRNA的剪接。靶向测序在1,155例散发性CHD患者中发现23例罕见突变。
■这里的发现证实,CHD7基因的从头功能丧失变异体是家族性CHD合并心外畸形的遗传原因,散发性CHD中致病性CHD7变异体的范围扩大。