Novel homozygous loss-of-function mutations in RP1 and RP1L1 genes in retinitis pigmentosa patients

ABSTRACT

Background: Retinitis pigmentosa (RP) is a heterogeneous group of ocular dystrophy. It is challenging to identify the underlying genetic defect in individuals with RP due to huge genetic heterogeneity. This study was designed to delineate the genetic defect(s) underlying RP in extended Saudi families and to describe the possible disease mechanism.

Materials and Methods: Fundus photography and a high definition optical coherence tomography (HD-OCT) were performed in order to detect the earlier stages of macular degeneration. Genomic DNA was extracted followed by genome-wide SNP genotyping and whole exome sequencing (WES). Exome data was filtered to identify the genetic variant(s) of interest.

Results: Clinical examination showed that affected individuals manifest key features of RP. The fundus exam shows pale optic disc and bone spicules at the periphery. OCT shows macular degeneration as early as at the age of 4 years. Whole genome scan by SNPs identified multiple homozygous regions. WES identified a 10 bps novel insertion mutation (c.3544_3545insAGAAAAGCTG; p.Ala1182fs) in the RP1 gene in both affected individuals of family A. Affected individual from family B showed a large insertion of 48 nucleotides in the coding part of the RP1L1 gene (c.3955_3956insGGACTAAAGTAATAGAAGGGCTGCAAGAAGAGAGGGTGCAGTTAGAGG; p.Ala1319fs). Sanger sequencing validates the autosomal recessive inheritance of the mutations.

Conclusion: The results strongly suggest that the insertion mutations in the RP1 and RP1L1 genes are responsible for the retinal phenotype in affected individuals from two families. Heterozygous individuals are asymptomatic carriers. We propose that the protective allele in other homozygous regions in heterozygous carriers contribute to the phenotypic variability in asymptomatic individuals.     

Retinitis pigmentosa associated with rhodopsin mutations: Correlation between phenotypic variability and molecular effects

Similar retinitis pigmentosa (RP) phenotypes can result from mutations affecting different rhodopsin regions, and distinct amino acid substitutions can cause different RP severity and progression rates. Specifically, both the R135L and R135W mutations (cytoplasmic end of H3) result in diffuse, severe disease (class A), but R135W causes more severe and more rapidly progressive RP than R135L. The P180A and G188R mutations (second intradiscal loop) exhibit a mild phenotype with regional variability (class B1) and diffuse disease of moderate severity (class B2), respectively. Computational and in vitro studies of these mutants provide molecular insights into this phenotypic variability.     

视网膜色素变性PRPF-31基因剪接位点突变及其相关表型特征研究

目的 研究一个常染色体显性遗传视网膜色素变性（ADRP）大家系的致病基因及其相关表型特征。方法 应用基因组扫描定位和突变检测法确定该家系的致病基因,并对其进行详细的家系调查,同时选取该家系不同代别中11例有症状的患者和7例无症状的个体,进行视网膜电图（ERG）、多焦视网膜电图（mERG）、心理物理学及荧光素眼底血管造影等检测。结果 在19号染色体PRPF-31基因5号内含子-1处发现一新的剪接位点突变（IVS5—1G→A）。家系中有症状的患者均在10岁以前发病,病情进展快而严重,呈Ⅰ型弥漫性视网膜色素变性（RP）表现。Goldmann视野检查,30岁以上患者动态视野大范围缺损,部分患者仅存颞侧视岛,静态视野阈值无法查出;mERG检测：双眼暗视a、b波振幅极度下降且低平,呈熄灭型;多焦视网膜电图显示双眼黄斑区及其周围视网膜反应密度显著降低;荧光素眼底血管造影显示黄斑中央凹周围色素上皮萎缩,呈“牛眼样”外观。7例无症状者中,1例经mERG、心理物理学及分子遗传学检测,证实其为轻症RP患者,另1例为疾病基因的杂合携带者。结论 PRPF-31基因5号内含子-1剪接位点突变（IVS5—1G→A）是ADRP的一种新的突变位点。该突变所致的ADRP表型主要为Ⅰ型弥漫性RP,同时,还存在基因外显不全和表现度不一的变异性表达。     

Efficacy of topical brinzolamide in children with retinal dystrophies

ABSTRACT

Background: Inherited retinal dystrophies are a leading cause of irreversible blindness in children in the United States. Topical carbonic anhydrase inhibitors have improved central vision and cystoid macular edema in patients with retinal dystrophies, but few studies have assessed their efficacy in children.

Materials and Methods: A retrospective chart review was performed with Institutional Review Board approval to identify pediatric patients with inherited retinal dystrophies who received topical brinzolamide at a single university center between 2008 and 2015. Serial visual acuity and central macular thicknesses were compared to assess the efficacy of brinzolamide.

Results: Seven subjects were identified who met the inclusion criteria. Four had juvenile X-linked retinoschisis, two had retinitis pigmentosa, and one had Leber congenital amaurosis. All were prescribed brinzolamide thrice daily; however, one patient was completely non-compliant. Four of the six treated patients exhibited a mild decrease in central macular thickness in both eyes during the study with all six treated patients having significantly improved vision at the first endpoint, 33.2 ± 8.2 months after treatment initiation. For treated patients, average visual acuity (LogMAR) ± standard error of the mean improved from 0.5 ± 0.04 pre-treatment to 0.3 ± 0.1 at the second endpoint, 50.2 ± 7.3 months after treatment initiation.

Conclusions: Mild anatomic improvement of macular cysts was seen in pediatric patients using brinzolamide. Visual acuity improvement occurred even without significant reduction in macular cysts. Further studies are needed to determine whether the beneficial effects of carbonic anhydrase inhibitors are sustained in children with inherited retinal degenerations.     

腹部推拿疗法治疗单纯性肥胖症临床疗效观察

目的：观察腹部推拿疗法治疗单纯性肥胖症的临床疗效.方法：选取符合诊断标准的单纯性肥胖症患者38例,施用腹部推拿疗法治疗.结果：痊愈1例,显效22例,有效11例,无效4例,总有效率89.47%.结论：腹部推拿疗法对于单纯性肥胖症的治疗具有良好的疗效.     

常染色体显性视网膜色素变性家系基因定位的研究与视紫红质基因突变的检测分析

对一常染色体显性视网膜色素变性 (autosomaldominantretinitispigmentosa ,ADRP)大家系进行基因定位 ,并检测该家系12名患者的视紫红质基因是否存在突变。方法 :采用多个已知位点的遗传标记对该ADRP家系进行连锁分析 ,确定致病基因的大致染色体位置 ;在所定位的染色体区域将RHO基因作为侯选基因进行直接测序检测突变。结果 :连锁分析结果发现遗传标记D3S12 92 ,当θ =0 1时有最大Lod值 =2 732 85 2 ,因此考虑该家系致病基因位于D3S12 92附近。直接测序结果发现该家系中大部分患者在RHO基因的第 3外显子序列 ,第 182密码子的第 2个碱基发生G→A置换突变 ,导致甘氨酸 (Gly)变为天冬氨酸 (Asp) ,命名为Gly -182 -Asp突变 ,而在 2例患者中则未发现突变 ;同时 ,在该家系正常成员以及正常对照者中均未发现此突变。结论 :ADRP存在分子水平的遗传异质性 ,某些ADRP是由于RHO基因突变所致。但是由于本研究所涉及的ADRP家系中尚有2名患者未找到RHO基因突变 ,故不能将Gly -182 -Asp突变认为是该家系的致病原因。在D3S12 92与RHO基因之间可能存在新的基因 ,还需进一步研究证明。     

视网膜色素变性家系的产前分子诊断

目的：对1例常染色体显性遗传视网膜色素变性家系患者所怀胎儿进行产前分子诊断。方法：应用聚合酶链反应（PCR）和直接测序技术法，对一常染色体显性遗传视网膜色素变性（ADRP）家系成员的所有现存人员的视紫红质基因的外显子进行测序分析。在采用STR位点分析方法排除母体基因组DNA污染后，应用DNA序列测定对胎儿-羊水基因组DNA进行分析。结果：该家系的25名成员中12名患者有视紫红质基因（rhodopsin，RHO）的512C〉T（P171L）突变，均呈杂合子，该错义突变使密码子171由CCA变成CTA。而未受累者的视紫红质基因表现为野生型。对该家系成员进行产前诊断，发现胎儿具有同种致病性突变。结论：视紫红质基因RHO的一种已知突变512C〉T（P171L）是该家系的病因，胎儿带P171L突变，产前诊断和早期干预能避免视网膜色素变性患儿的出生。     

针刺治疗视网膜色素变性的组穴规律分析

目的:基于数据挖掘技术分析文献中针刺治疗视网膜色素变性穴位的组方规律。方法:检索国家知识基础设施数据库（CNKI）、中国学术期刊数据库（CSPD）、中文科技期刊数据库（CCD）文献中治疗视网膜色素变性所使用的穴位处方,使用中医传承计算平台（V3.1）进行数据挖掘,分析针刺治疗视网膜色素变性的取经、选穴和配伍规律。结果:共纳入文献47篇,应用频次前5位的腧穴为球后、睛明、太阳、足三里、合谷;奇穴选用频次最高,经脉选用频次前3位依次为足太阳膀胱经、足少阳胆经、足阳明胃经;取穴部位以头颈部选取最多;其次为下肢部和上肢部。结论:针刺治疗视网膜色素变性的核心经脉为足太阳膀胱经、足少阳胆经及足阳明胃经,核心组穴为球后、睛明及太阳,配以足三里、合谷、光明、三阴交等穴,其取穴规律以局部取穴以及邻近取穴直达病所为主,远端取穴以足三里、合谷等辅以调理脏腑经络。     

Factors associated with visual acuity in patients with cystoid macular oedema and Retinitis Pigmentosa

Purpose: Retinitis pigmentosa is the most common inherited retinal dystrophy. The factors associated with visual acuity in patients with other retinal diseases are well known, but are poorly understood in patients with retinitis pigmentosa. This knowledge is useful for prognosis and to support secondary endpoints in clinical trials.

Methods: We conducted a cross-sectional study of consecutive patients recruited from the inherited retinal disease service from January 2012 to December 2012. Central macular thickness (CMT) was measured using spectral domain optical coherence tomography.

Results: Data were available for 81 patients and 162 eyes. After multivariable analyses, older age, earlier age of onset of symptoms, and thicker CMT were associated with lower visual acuity. Gender and inheritance pattern were not associated with visual acuity. Each decade older age, younger age of onset, and thicker CMT was associated with 0.12, 0.10, and 0.11 worse logarithm of the minimal angle of resolution units of visual acuity, respectively (p < 0.05 for all).

Conclusions: Age, age of onset, and CMT are associated with visual acuity and important factors to measure in studies of retinitis pigmentosa.