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。     

Adrenomedullin plasma concentrations in patients with retinitis pigmentosa

PURPOSE: To evaluate the relationship between retinitis pigmentosa (RP) and plasma adrenomedullin (ADM) levels. METHODS: Blood samples were obtained from a group of 40 consecutive patients with RP matched with 35 healthy subjects (HS) as control. We carried out a complete ophtalmological examination. The study group included 26 patients with RP and 14 patients with syndromic RP. Plasma ADM levels were determined in duplicate with a specific radioimmunoassay method. RESULTS: In the HS plasma ADM levels were 13.7 +/- 6.1 pg/mL. The mean of plasma ADM concentrations in all patients with RP (23.4 +/- 10.7 pg/mL) was significantly (P < 0.0001) higher than that of HS. Moreover, in the syndromic RP patients, plasma ADM levels (28.6 +/- 14.35 pg/ml) were higher than those of HS and RP patients (P < 0.0017). CONCLUSION: The increase of plasma ADM levels in RP patients may be a response to photoreceptor damage.     

视网膜色素变性患者视觉电生理学检测指标分析

目的对视网膜色素变性患者的闪光视网膜电图(flash electroretinogram,F-ERG)、图形视觉诱发电位(pattern visual evoked potential,P-VEP)及闪光视觉诱发电位(flash visual evoked potential,F-VEP)检查结果进行分析,揭示视网膜色素变性(retinitis pigmentosa,RP)患者视觉电生理检查的特征及视网膜色素变性患者的发病机制。方法使用罗兰RETIport电生理仪,记录视网膜色素变性患者43例86眼的F-ERG、P-VEP及F-VEP。结果受检的86只视网膜色素变性眼中,ERG中暗视视杆细胞反应为熄灭型者占83.7%、暗适应最大反应为熄灭型者占57%、明视视锥细胞反应为熄灭型者占57%、闪烁光反应熄灭型者占43%、Ops熄灭型者占62.8%;P-VEP无波形的患者占26.7%;F-VEP均引出波形。其中视力<0.3与视力≥0.3患者相比,各种电生理检查指标均有显著性降低。视力≥0.3患者的视力与各项电生理检查指标进行相关分析,均无相关性。结论RP患者的F-ERG各反应与VEP反应都有不同程度的改变。     

Breakpoint characterization of a novel ～59?kb genomic deletion on 19q13.42 in autosomal-dominant retinitis pigmentosa with incomplete penetrance

The aim of this study was to identify and characterize the underlying molecular mechanisms in autosomal-dominant retinitis pigmentosa (adRP) with incomplete penetrance in two Swedish families. An extended genealogical study and haplotype analysis indicated a common origin. Mutation identification was carried out by multiplex ligation-dependent probe amplification (MLPA) and sequencing. Clinical examinations of adRP families including electroretinography revealed obligate gene carriers without abnormalities, which indicated incomplete penetrance. Linkage analysis resulted in mapping of the disease locus to 19q13.42 (RP11). Sequence analyses did not reveal any mutations segregating with the disease in eight genes including PRPF31. Subsequent MLPA detected a large genomic deletion of 11 exons in the PRPF31 gene and, additionally, three genes upstream of the PRPF31. Breakpoints occurred in intron 11 of PRPF31 and in LOC441864, ‘similar to osteoclast-associated receptor isoform 5.'' An almost 59 kb deletion segregated with the disease in all affected individuals and was present in several asymptomatic family members but not in 20 simplex RP cases or 94 healthy controls tested by allele-specific PCR. A large genomic deletion resulting in almost entire loss of PRPF31 and three additional genes identified as the cause of adRP in two Swedish families provide an additional evidence that mechanism of the disease evolvement is haploinsufficiency. Identification of the deletion breakpoints allowed development of a simple tool for molecular testing of this genetic subtype of adRP.     

Retinal organization in the retinal degeneration 10 (rd10) mutant mouse: a morphological and ERG study

Retinal degeneration 10 (rd10) mice are a model of autosomal recessive retinitis pigmentosa (RP), identified by Chang et al. in 2002 (Vision Res. 42:517-525). These mice carry a spontaneous mutation of the rod-phosphodiesterase (PDE) gene, leading to a rod degeneration that starts around P18. Later, cones are also lost. Because photoreceptor degeneration does not overlap with retinal development, and light responses can be recorded for about a month after birth, rd10 mice mimic typical human RP more closely than the well-known rd1 mutants. The aim of this study is to provide a comprehensive analysis of the morphology and function of the rd10 mouse retina during the period of maximum photoreceptor degeneration, thus contributing useful data for exploiting this novel model to study RP. We analyzed the morphology and survival of retinal cells in rd10 mice of various ages with quantitative immunocytochemistry and confocal microscopy; we also studied retinal function with the electroretinogram (ERG), recorded between P18 and P30. We found that photoreceptor death (peaking around P25) is accompanied and followed by dendritic retraction in bipolar and horizontal cells, which eventually undergo secondary degeneration. ERG reveals alterations in the physiology of the inner retina as early as P18 (before any obvious morphological change of inner neurons) and yet consistently with a reduced band amplification by bipolar cells. Thus, changes in the rd10 retina are very similar to what was previously found in rd1 mutants. However, an overall slower decay of retinal structure and function predicts that rd10 mice might become excellent models for rescue approaches.     

Calpain activity in retinal degeneration

Retinal degenerations such as retinitis pigmentosa (RP) or glaucoma are a major cause of blindness in humans. Understanding the mechanisms underlying the various types of retinal degeneration is a pre-requisite for the development of rational therapies for these diseases. Activation of the calcium dependent protease, calpain, has been suggested to play an important role in cell death in various neuronal tissues including the retina. Improved detection and analysis of calpain activity during degenerative processes is likely to expand the list of pathological conditions with calpain involvement. We give a short overview of the methods available for the detection of calpain activity, and briefly discuss properties of calpain inhibitors. We then discuss the role of calpains in different cell death mechanisms and review existing work on retinal degeneration and the possible involvement of calpains therein. The implication of calpains in retinal cell death raises the possibility to use calpain inhibitors to prevent or delay retinal degeneration.     

Paradoxical opsin expressing cells in the inner retina that are augmented following retinal degeneration

Here we reveal a population of cells that express cone photoreceptor opsins that are located in the inner retina, distant from outer retinal photoreceptors. These cells are present in rodents and human. They also express a range of key proteins critical in the cone phototransduction cascade and make contact with other retinal neurons. Their opsins are not generally confined to cellular specialized regions but are present throughout the plasma membrane, although their nuclear configurations are similar to those of outer retinal cones. This population is distinct from the ganglion cells that contain melanopsin and which are known to be inner retinal irradiance detectors regulating circadian behaviour. Surprisingly, the size of the population of short wavelength opsin positive cells in the ganglion cell layer is plastic. In normal animals their number declines with age. However, their numbers increase significantly in response to outer retinal photoreceptor loss, probably by drawing on a pool of inner retinal cells that express cone specific markers, but not opsins.     

USH1H, a novel locus for type I Usher syndrome, maps to chromosome 15q22-23

Usher syndrome (USH) is a hereditary disorder associated with sensorineural hearing impairment, progressive loss of vision attributable to retinitis pigmentosa (RP) and variable vestibular function. Three clinical types have been described with type I (USH1) being the most severe. To date, six USH1 loci have been reported. We ascertained two large Pakistani consanguineous families segregating profound hearing loss, vestibular dysfunction, and RP, the defining features of USH1. In these families, we excluded linkage of USH to the 11 known USH loci and subsequently performed a genome-wide linkage screen. We found a novel USH1 locus designated USH1H that mapped to chromosome 15q22-23 in a 4.92-cM interval. This locus overlaps the non-syndromic deafness locus DFNB48 raising the possibility that the two disorders may be caused by allelic mutations.     

伴中性粒细胞浸润的色素性荨麻疹

报告1例伴中性粒细胞浸润的色素性荨麻疹．患儿女，5岁。躯干、四肢色素沉着斑伴瘙痒1年余．体格检查示躯干、四肢广泛分布大量色素性斑片及少量红斑、抓痕．组织病理检查示真皮内大量中性粒细胞浸润及核尘，未见血管纤维素样坏死．高倍镜下见血管周围较多肥大细胞浸润．诊断为伴中性粒细胞浸润的色素性荨麻疹。