背景:原发性卵巢功能不全(POI)定义为40岁之前卵巢功能停止,以闭经为特征,不孕症,促性腺激素水平升高和性类固醇缺乏症。POI的表型是异质的,包括孤立和综合征形式。Perrault综合征(PS),女性40岁前表现为感音神经性听力损失(SNHL)和卵巢功能障碍,是一种综合征性POI。遗传缺陷在POI的发病机制中起着至关重要的作用。
结果:为了说明Perrault综合征的遗传原因,我们对该疾病的一个谱系进行了全外显子组测序(WES),并在TWNK中鉴定出一个新的纯合突变(c.1388G>A,p.R463Q)。TWNK在线粒体中编码六聚体DNA解旋酶,并在mtDNA复制中起关键作用。为了确定新突变对线粒体功能的影响,我们通过用EB病毒体外感染家族成员的淋巴细胞来产生永生化细胞系。功能研究发现,TWNKp.R463Q损害了线粒体的mtDNA复制和呼吸电位,而ROS水平未受影响。
结论:我们的研究提供了TWNK突变通过线粒体功能失调损害卵巢功能的证据。此外,考虑到这里的患者比SNHL更早出现POI,位于TWNK不同基因座的特定变异可能诱导异质性表型,这表明POI患者的基因筛查对于早期识别其他疾病或综合征性POI的其他表型是有用的。
BACKGROUND: Primary ovarian insufficiency (POI) is defined as cessation of ovarian function before the age of 40 years, which is characterized by amenorrhoea, infertility, elevated gonadotrophin level and sex-steroid deficiency. The phenotypes of POI are heterogeneous, including isolated and syndromic forms. Perrault syndrome (PS), characterized by sensorineural hearing loss (SNHL) and ovarian dysfunction before 40 years in females, is one type of syndromic POI. Genetic defects play a vital role in the pathogenesis of POI.
RESULTS: To illustrate the genetic causation of Perrault syndrome, we performed whole exome sequencing (WES) in one pedigree with the disease, and identified a novel homozygous mutation in TWNK (c.1388G > A, p.R463Q). TWNK encodes a hexameric DNA helicase in mitochondria and plays a critical role in mtDNA replication. In order to determine the effect of the novel mutation on the mitochondrial function, we generated immortalized cell lines by infecting lymphocytes from the family members with EB virus in vitro. Functional studies found that TWNK p.R463Q impaired mtDNA replication and the respiration potential of mitochondria, while the ROS level remains unaffected.
CONCLUSIONS: Our study provided evidence that TWNK mutation impaired the ovarian function by dysfunctional mitochondria. Moreover, considering the patients here presented POI onset earlier than SNHL, specific variants localizing in different locus of TWNK might induce heterogeneous phenotypes, indicating that the genetic screening of patients with POI would be useful for early recognition of other disease or other phenotypes of syndromic POI.