背景:Usher综合征(USH)包括一组以先天性感觉神经性听力损失(SNHL)和色素性视网膜炎(RP)为特征的疾病。我们描述了临床发现,自然史,以及在SardiNIA项目队列中进行大规模筛查以确定与眼部疾病相关的定量特征的USH患者的分子分析。
方法:我们从6148名健康受试者的队列中确定了3个受USH影响的家庭。9名受试者呈现病理表型,SNHL和RP。所有患者及其家庭成员都接受了完整的眼科检查,包括最佳矫正视力。裂隙灯生物显微镜,眼底镜检查,眼底自发荧光,谱域光学相干层析成像,和电生理测试。用临床听力计进行听力学评估。使用与全基因组序列数据整合的几个阵列进行基因分型,为分析的每个受试者提供平均分布的约2200万个标记。分子诊断专注于分析以下候选基因:MYO7A,USH1C,CDH23,PCDH15,USH1,CIB2,USH2A,GPR98、DFNB31、CLRN1和PDZD7。
结果:在所有患者中,USH2A基因中的单个错义因果变异被鉴定为纯合状态,在未受影响的父母中鉴定为杂合状态。多个具有相同表型严重程度的纯合子患者的存在表明,撒丁岛USH表型是对特定致病变异相关单倍型的创始人效应的结果。一般撒丁岛人口中杂合子的频率为1.89。此外,为了提供对usherin结构和由小致病性框架内变异引起的病理机制的新见解,像p.Pro3272Leu,对天然和突变的蛋白质-蛋白质和蛋白质-配体复合物进行了分子动力学模拟,预测了蛋白质的不稳定,自由能变化降低。
结论:我们的结果表明我们的方法对USH的遗传诊断是有效的。根据杂合频率,建议在普通人群和高危家庭或家族性USH人群中进行这种变异的靶向筛查.这可以导致更准确的分子诊断,更好的遗传咨询,和改进的分子流行病学数据对未来的干预计划至关重要。
背景:我们没有对参与者进行任何与健康相关的干预。
BACKGROUND: Usher syndrome (USH) encompasses a group of disorders characterized by congenital sensorineural hearing loss (SNHL) and retinitis pigmentosa (RP). We described the clinical findings, natural history, and molecular analyses of USH patients identified during a large-scale screening to identify quantitative traits related to ocular disorders in the SardiNIA project cohort.
METHODS: We identified 3 USH-affected families out of a cohort of 6,148 healthy subjects. 9 subjects presented a pathological phenotype, with SNHL and RP. All patients and their family members underwent a complete ophthalmic examination including best-corrected visual acuity, slit-lamp biomicroscopy, fundoscopy, fundus autofluorescence, spectral-domain optical coherence tomography, and electrophysiological testing. Audiological evaluation was performed with a clinical audiometer. Genotyping was performed using several arrays integrated with whole genome sequence data providing approximately 22 million markers equally distributed for each subject analyzed. Molecular diagnostics focused on analysis of the following candidate genes: MYO7A, USH1C, CDH23, PCDH15, USH1G, CIB2, USH2A, GPR98, DFNB31, CLRN1, and PDZD7.
RESULTS: A single missense causal variant in USH2A gene was identified in homozygous status in all patients and in heterozygous status in unaffected parents. The presence of multiple homozygous patients with the same phenotypic severity of the syndromic form suggests that the Sardinian USH phenotype is the result of a founder effect on a specific pathogenic variant related haplotype. The frequency of heterozygotes in general Sardinian population is 1.89. Additionally, to provide new insights into the structure of usherin and the pathological mechanisms caused by small pathogenic in-frame variants, like p.Pro3272Leu, molecular dynamics simulations of native and mutant protein-protein and protein-ligand complexes were performed that predicted a destabilization of the protein with a decrease in the free energy change.
CONCLUSIONS: Our results suggest that our approach is effective for the genetic diagnosis of USH. Based on the heterozygous frequency, targeted screening of this variant in the general population and in families at risk or with familial USH can be suggested. This can lead to more accurate molecular diagnosis, better genetic counseling, and improved molecular epidemiology data that are critical for future intervention plans.
BACKGROUND: We did not perform any health-related interventions for the participants.