低深度全基因组测序检测以甲状腺功能减退起病的Williams-Beuren综合征一例

目的探讨1例不明原因智力低下、生长发育迟缓、具有特殊面容及甲状腺功能减退的5岁男性患儿的临床表型和遗传学病因。方法用常规G显带技术分析患儿及其父母染色体核型,应用全外显子组测序及低深度全基因组测序技术(low-coverage massively parallel CNV sequencing,CNV-seq)对患儿进行可能致病突变及染色体拷贝数变异的分析。结果患儿染色体核型为46,XY,其父母未见明显的染色体异常。CNV-seq分析显示患儿在染色体7q11.23区域存在大小为1.56 Mb的杂合性缺失,缺失区域包含24个编码蛋白质的基因,其缺失与Williams-Beuren综合征相关。通过对其父母检测CNV-seq,发现该缺失为一新发缺失。结论本研究用CNV-seq技术确诊了1例以甲状腺功能减退起病的Williams-Beuren综合征患儿,有助于提高临床医师对Williams-Beuren综合征表型与发病机制的认识。

Diagnosis of one case of Williams-Beuren syndrome presenting with hypothyroidism by low-coverage massively parallel CNV sequencing

Objective To explore the clinical phenotypes and the genetic causes for a 5 years old boy with unexplained growth retardation,developmental delay,special face,and hypothyroidism.Methods Routine G-banding was performed to analyze the karyotype of the patient and his parents.In addition,whole exome sequencing and low-coverage massively parallel CNV sequencing(CNV-seq)were used to determine the potentially pathogenic variants as well as the copy number variations(CNVs).Results The child′s karyotype was 46,XY,and his parents′karyotypes were normal.However,CNV-seq identified a heterozygous deletion of 1.56 Mb on chromosome region 7q11.23 in the patient,including 24 protein-coding genes,which were associated with Williams-Beuren syndrome.His parents′results of CNV-seq were normal,indicating a de novo CNVs.Conclusion A Williams-Beuren syndrome child presenting with hypothyroidism was diagnosed by CNV-seq,which would contribute to further understanding the clinical phenotypes and pathogenesis of this disease.