双等位基因PRKCZ功能缺失变异与成人发病型视网膜色素变性

文献信息

中文摘要

重要性： 遗传性视网膜疾病是遗传异质性疾病，其中视网膜色素变性（RP）是最常见的形式；尽管已涉及90多个基因，许多RP病例在分子层面仍未得到解决。
目的： 描述与PRKCZ功能缺失变异相关的成人发病型RP表型，分析该疾病的临床特征，并探讨其潜在疾病机制。
设计、设置和参与者： 在这项病例系列研究中，对通过国际研究和诊断项目招募的未解决儿童期及成人发病型视网膜疾病个体进行了基因组分析。对受累个体进行了详细的临床特征分析。采用原代和转导细胞实验方法进行体外分析以验证基因组发现。基因组分析于2023年10月至2025年12月进行；功能研究于2024年1月至2026年5月进行。
暴露： 新型RP疾病候选基因PRKCZ中的双等位基因可能致病变异。
主要结局和指标： 主要结局是与成人发病型RP相关的双等位基因PRKCZ失活变异的遗传、临床和功能效应。进行了详细的眼科评估以描述临床表型。在患者来源的成纤维细胞和转导细胞系中进行功能分析，以验证破坏性变异对PRKCZ转录本加工和PKCζ功能的影响。
结果： 在约4500名接受检测的未解决儿童期及成人发病型视网膜疾病个体中，在来自10个无亲缘关系家庭的13名受累个体中鉴定出6个双等位基因PRKCZ变异，其中5个预计导致功能缺失（移码、无义或剪接改变变异）。13名受累个体中有6名（46%）为女性。大多数病例携带复发性移码变异（c.139_140del；p.Met47Valfs*19）。所有变异均选择性影响编码N端Phox和Bem1（PB1）结构域的长PRKCZ转录本。临床上，PRKCZ相关RP表现为成人发病（18-49岁）、进行性夜盲、周边视野缩窄以及最终的中心视力丧失。4名个体表现出成人发病型感音神经性听力损失。患者来源成纤维细胞的功能研究显示长PRKCZ异构体选择性丢失、纤毛发生受损和线粒体组织改变，并在稳定的PRKCZ敲低细胞系中得到验证。结构建模和共免疫沉淀实验表明，该错义变异与PB1结构域介导的蛋白质-蛋白质相互作用破坏相关。
结论与意义： 在这项病例系列研究中，PRKCZ双等位基因失活变异与成人发病型RP相关，其机制涉及视网膜富集的长转录本的异构体特异性机制。这些发现扩展了RP的遗传谱，并强调PRKCZ是可能与成人发病型视网膜变性相关的临床相关基因。

英文摘要

IMPORTANCE: Inherited retinal diseases are genetically heterogeneous disorders, with retinitis pigmentosa (RP) representing the most common form; although more than 90 genes have been implicated, many RP cases remain molecularly unsolved.
OBJECTIVES: To describe an adult-onset RP phenotype associated with loss-of-function variants in PRKCZ, profile the clinical features of this disorder, and investigate the underlying disease mechanism.
DESIGN, SETTING, AND PARTICIPANTS: In this case series study, genomic analyses were performed in individuals with unsolved childhood- and adult-onset retinal disease recruited through international research and diagnostic programs. Detailed clinical characterization was conducted in affected individuals. In vitro analyses were carried out to validate the genomic findings using primary and transduced cell-based experimental approaches. Genomic analyses were performed from October 2023 to December 2025; functional studies were carried out from January 2024 to May 2026.
EXPOSURE: Bi-allelic likely pathogenic variants in a novel RP disease gene candidate, PRKCZ.
MAIN OUTCOMES AND MEASURES: The primary outcome was genetic, clinical, and functional effects of bi-allelic PRKCZ inactivating variants associated with adult-onset RP. A detailed ophthalmologic assessment was conducted to characterize the clinical phenotype. Functional analyses in patient-derived fibroblasts and transduced cell lines were performed to validate the consequence of disruptive variants on PRKCZ transcript processing and PKCζ function.
RESULTS: Among approximately 4500 individuals with unsolved childhood- and adult-onset retinal disease tested, 6 bi-allelic PRKCZ variants were identified in 13 affected individuals from 10 unrelated families, 5 of which were predicted to lead to loss of function (frameshift, nonsense, or splice-altering variants). Six of 13 affected individuals (46%) were female. Most cases carried a recurrent frameshift variant (c.139_140del; p.Met47Valfs*19). All variants selectively affected the long PRKCZ transcript encoding the N-terminal Phox and Bem1 (PB1) domain. Clinically, PRKCZ-associated RP showed adult onset (18-49 years), progressive night blindness, peripheral visual field constriction, and eventual central vision loss. Four individuals exhibited adult-onset sensorineural hearing loss. Functional studies in patient-derived fibroblasts demonstrated selective loss of the long PRKCZ isoform, impaired ciliogenesis, and altered mitochondrial organization, which were validated in stable PRKCZ knockdown cell lines. Structural modeling and coimmunoprecipitation assays indicated that the missense variant was associated with the disruption of PB1 domain-mediated protein-protein interactions.
CONCLUSIONS AND RELEVANCE: In this case series study, bi-allelic inactivating variants in PRKCZ were associated with adult-onset RP with an isoform-specific mechanism involving the long retinal-enriched transcript. These findings expand the genetic spectrum of RP and highlight PRKCZ as a potentially clinically relevant gene implicated in adult-onset retinal degeneration.