Objective: To explore the diagnostic value of chromosome karyotype analysis, chromosomal microarray analysis (CMA) and whole exome sequencing (WES) in microcephaly. Methods: A total of 9 cases of microcephaly fetuses diagnosed by prenatal ultrasound or children with microcephaly diagnosed after birth were selected from the Sixth Affiliated Hospital of Guangzhou Medical University from January 2014 to August 2022.Karyotype analysis and/or CMA were used to detect. The cases with negative karyotype analysis and CMA results were further sequenced by trio-based WES (Trio-WES). Then the coding genes contained in the pathogenic copy number variation (CNV) fragments were analyzed by gene ontology (GO) enrichment. The genes related to the development of the central nervous system contained in the pathogenic CNV and the pathogenic genes found by Trio-WES were combined for gene interaction network analysis. Results: In this study, 9 cases of microcephaly were recruited, with the time of diagnosis ranged from 23 weeks of gestation to 7 years after birth, and the head circumference of fetus or children ranged from 18.3 to 42.5 cm (-7SD to -2SD). Karyotype analysis was detected in all 9 cases and no abnormality result was found. Eight cases were detected by CMA, and one abnormal was found. Five cases were detected by Trio-WES, and two cases were detected with likely pathogenic genes. The GO enrichment analysis of the coding gene in the 4p16.3 microdeletion (pathogenic CNV) region showed that: in biological process, it was mainly concentrated in phototransduction, visible light; in terms of molecular function, it was mainly concentrated in fibroblast growth factor binding; in terms of cell components, it was mainly concentrated in rough endoplasmic reticulum. Gene interaction network analysis suggested that CDC42 gene could interact with CTBP1, HTT and ASPM gene. Conclusions: CMA could be used as a first-line detection technique for microcephaly. When the results of chromosome karyotype analysis and/or CMA are negative, Trio-WES could improve the detection rate of pathogenicity of microcephaly.
目的： 探讨染色体核型分析、染色体微阵列分析（CMA）及全外显子测序（WES）技术在小头畸形遗传学诊断中的价值。 方法： 选取2014年1月至2022年8月在广州医科大学附属第六医院产前诊断门诊就诊，产前超声检查诊断为小头畸形的胎儿或出生后诊断为小头畸形的患儿共计9例，行染色体核型分析和（或）CMA检测，对染色体核型分析和CMA检测结果阴性的患儿进一步行核心家系WES（Trio-WES）检测，再对致病性拷贝数变异（CNV）片段包含的编码基因进行基因本体（GO）功能注释分析，将致病性CNV包含的与中枢神经系统发育相关的基因及WES检测发现的致病基因联合进行基因相互作用网络分析。 结果： 9例小头畸形患儿中，3例合并其他结构畸形（3/9）；诊断时间为孕23周~出生后7岁；诊断时头围18.3~42.5 cm（-7SD~-2SD）。9例小头畸形患儿均行染色体核型分析，结果均未见异常；8例患儿行CMA检测，检出异常1例，异常检出率为1/8；5例行Trio-WES检测，2例检出可能致病性基因，致病性检出率为2/5。染色体4p16.3微缺失（为致病性CNV）区域内编码基因的GO富集分析显示，主要富集于可见光光传导等生物学过程，成纤维细胞生长因子结合等分子功能，粗面内质网等细胞组分。基因相互作用网络分析提示，CDC42基因可以与CTBP1、HTT、ASPM基因发生相互作用。 结论： CMA检测可作为小头畸形的一线检测技术，染色体核型分析和（或）CMA检测结果阴性时，Trio-WES检测可提高小头畸形的致病性检出率。.