Wu Shaomin, Zheng Yingchun, Xu Cailing, Fu Jiahui, Xiong Fu, Yang Fang
Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China.
Prenatal Diagnosis Center, Affiliated Dongguan Hospital, Southern Medical University (Dongguan People's Hospital), Dongguan, China.
Front Pediatr. 2022 Jan 20;9:811812. doi: 10.3389/fped.2021.811812. eCollection 2021.
To analyze genetic mutations in a Chinese pedigree affected with Alpha-thalassemia X-linked intellectual disability syndrome, providing a precise diagnosis and genetic counseling.
Clinical data was collected. A novel alternative splicing variant detected by whole-exome sequencing was validated by Sanger sequencing. The functional effect of the mutation was predicted with Mutation Tasting. The analysis of 5' splice site score was estimated with MaxEntScan. Changes in amino acid sequencing were predicted with Mutalyzer. The tertiary structures of the wild type and mutation-carrying protein were predicted by I-TASSER. RNA was extracted from peripheral blood lymphocytes from the proband, his mother and a healthy control. Quantitative Real-Time PCR was used to detect mRNA expression.
The proband presented with severe intellectual disability, developmental delay, characteristic facies, seizures and cryptorchidism. A novel hemizygous duplication mutation in the gene in a splice site between exons 3 and 4, NM_000489: c.189+1dupG, was identified with WES in the proband. Sanger sequencing confirmed that the mutation was inherited from his mother, who carried a heterozygous mutation, while his father was not affected. Bioinformatics analysis indicated that the splicing region where the mutation was located is highly conserved and the variant was damaging, producing a truncated protein due to the premature translation of a stop codon. Sanger sequencing with the Quantitative Real-Time PCR product containing a G base inserted between bases 189 and 190. The level of mRNA expression showed that gene transcription decreased due to the mutation ( < 0.05).
A novel mutation in was found in this pedigree and was confirmed to be pathogenic through functional studies. Our research expanded the spectrum of gene mutations, providing a precise diagnosis and a basis for genetic counseling.
分析一个患有X连锁智力障碍综合征伴α地中海贫血的中国家系中的基因突变情况，以提供准确的诊断和遗传咨询。
收集临床资料。通过全外显子组测序检测到的一个新的剪接变异体，用桑格测序法进行验证。用突变预测软件预测该突变的功能效应。用MaxEntScan评估5'剪接位点得分。用Mutalyzer预测氨基酸序列的变化。用I-TASSER预测野生型和携带突变蛋白的三级结构。从先证者、其母亲和一名健康对照的外周血淋巴细胞中提取RNA。采用定量实时荧光定量PCR检测mRNA表达。
先证者表现为严重智力障碍、发育迟缓、特殊面容、癫痫发作和隐睾症。通过全外显子组测序在先证者中鉴定出一个位于外显子3和4之间剪接位点的新的半合子重复突变，NM_000489:c.189+1dupG。桑格测序证实该突变遗传自其母亲，其母亲为杂合突变，而其父亲未受影响。生物信息学分析表明，突变所在的剪接区域高度保守，该变异具有损害性，由于终止密码子的过早翻译产生了截短蛋白。对包含在189和190位碱基之间插入一个G碱基的定量实时荧光定量PCR产物进行桑格测序。mRNA表达水平显示，由于该突变，基因转录下降（<0.05）。
在这个家系中发现了一个新的 基因突变，并通过功能研究证实其具有致病性。我们的研究扩展了 基因突变谱，为准确诊断和遗传咨询提供了依据。
