中国33 104 例育龄期人群CYP21A2 基因致病变异携带者筛查:基于PCR-NGS技术的前瞻性多中心研究


Carrier screening for CYP21A2 in a Chinese cohort of 33 104 reproductive-aged individuals: A prospective multicenter study using PCR-NGS technology


  • 摘要: 背景 21-羟化酶缺乏症(21-hydroxylase deficiency,21-OHD)是由CYP21A2 基因变异引起的常染色体隐性遗传病。CYP21A2 基因与其高度同源的假基因CYP21A1P之间易发生重组,二代测序技术应用于该基因携带者筛查存在挑战,且目前针对大规模普通育龄人群的携带者筛查数据有限。目的 明确我国普通育龄人群CYP21A2 基因致病变异的携带率与变异谱,为开展人群筛查提供关键数据基础;评估基于PCR富集真基因结合二代测序(polymerase chain reaction-next-generation sequencing,PCR-NGS)的新型检测方案,提升筛查的准确性与可行性。方法 本研究为前瞻性、多中心调查性研究。2022年7 月至2023 年10 月,从全国12 家三甲医院招募普通育龄期夫妇。采集外周血样本,使用特异性引物PCR富集CYP21A2真基因片段,进行二代测序及生物信息学分析。对筛查出的高危夫妇及携带多个变异的个体,采用三代测序进行验证。结果 在全国12 家临床中心招募33 104 例育龄期人员,包含16 494 对夫妇及116 例单独筛查的女性。二代测序共检出636 例携带者,经三代测序验证,在二代测序提示为多个变异携带者的个体中,3 例为致病变异呈反式排列的轻型患者,2 例为因基因重组导致真基因重复的健康个体,最终确认携带者631 例。人群总携带率为1/52.46,女性携带者率为1/53.92(308/16 610),男性携带者率为1/51.07(323/16 494)。共检出34 种致病变异,其中88.01%源于假基因的微转换。最常见的三种变异为:c.844G>T(0.31%)、c.293-13C>G(0.22%)和c.518T>A(0.15%)。结论 本研究在大样本人群中进行调查,揭示了中国育龄人群CYP21A2 基因的致病变异携带情况。所建立的PCR-NGS方案能有效克服假基因干扰,适用于大规模携带者筛查,但需注意其对大片段重组的检测局限,临床应用时应结合遗传咨询与必要补充验证。

     

    Abstract: Background 21-Hydroxylase deficiency (21-OHD) is an autosomal recessive disorder caused by pathogenic variants in the CYP21A2 gene. The CYP21A2 gene and its highly homologous pseudogene, CYP21A1P, are prone to recombination events, posing significant challenges for carrier screening using next-generation sequencing (NGS). Furthermore, data on large-scale carrier screening for CYP21A2 in the general reproductive-aged population remain limited. Objective To determine the carrier frequency and variant spectrum of CYP21A2 pathogenic variants in the general reproductive-aged Chinese population, thereby providing essential data to inform population-based screening. Additionally, to evaluate the performance of a novel PCR-based enrichment strategy combined with NGS (PCR-NGS) designed to overcome pseudogene interference and enhance the accuracy and feasibility of screening. Methods This prospective, multicenter observational study recruited 33 104 asymptomatic cases planning pregnancy or in early pregnancy from 12 tertiary hospitals across China from July 2022 to October 2023. Genomic DNA was extracted from peripheral blood. The CYP21A2 functional gene was specifically enriched via PCR using unique primers, followed by targeted NGS and bioinformatic analysis. High-risk couples and individuals carrying multiple variants identified by NGS were subsequently validated using third-generation sequencing (TGS). Results Initial NGS screening identified 636 carriers. TGS validation revealed that among individuals flagged with multiple variants, 3 were mild patients with pathogenic variants in trans, and 2 were healthy individuals with true gene duplication. After correction, the final cohort comprised 631 carriers, yielding an overall carrier frequency of 1/52.46. The carrier frequency was 1/53.92 (308/16 610) in females and 1/51.07 (323/16 494) in males. Thirtyfour distinct pathogenic variants were detected, with 88.01% originating from pseudogene-derived microconversions. The three most prevalent variants were c.844G>T (allele frequency 0.31%), c.293-13C>G (0.22%), and c.518T>A (0.15%). Conclusion This study systematically delineates the CYP21A2 pathogenic variant landscape in the Chinese reproductive-aged population. The established PCR-NGS protocol effectively overcomes pseudogene interference, demonstrating its suitability for large-scale carrier screening. However, its inherent limitation in detecting large gene rearrangements necessitates integration with comprehensive genetic counseling and confirmatory testing for specific genotypes in clinical practice.

     

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