NDP基因新突变G113D导致X连锁隐性遗传家族性渗出性玻璃体视网膜病变

目的对一个X连锁隐性遗传家族性渗出性玻璃体视网膜病变（FEVR）家系进行致病基因的突变筛查研究。设计基因研究。研究对象一个中国北方FEVR家系。方法应用聚合酶链式反应（PCR）和sanger测序法对FEVR的致病候选基因LRP5、FZD4、TSPAN12和NDP的全部外显子进行突变筛查,将测序结果与Genebank数据库的正常序列进行比对,将所发现的候选基因碱基改变在50个无关正常对照人群中进行PCR和测序验证。主要指标基因序列。结果在NDP基因的外显子3发现一个半合子错义突变G113D与家系男性先证者共分离,先证者母亲显示为G113D的杂合携带者,该突变在家系其他成员及正常人群中没有检测到。结论该家系的FEVR系由ⅣDP基因外显子3的一个新的错义突变G113D导致。     

原纤维蛋白1基因新突变导致单纯性晶状体异位

目的 研究我国单纯性晶状体异位家系的致病基因,并确定基因突变。方法 对单纯性晶状体异位一家系进行临床研究和系谱分析。采集家系中7例患者和3例健康成员的静脉血,提取基因组DNA。通过连锁分析确定致病基因的染色体位点后,应用聚合酶链反应(PCR)扩增原纤维蛋白(FBN)1基因外显子,直接测序确定致病的基因突变。采用PCR和限制性内切酶法进行群体分析。结果单纯性晶状体异位患者的FBN1基因外显子6发生了错义突变,cDNA 640位的鸟嘌呤被腺嘌呤取代(13640A);对应的甘氨酸改变为丝氨酸(G214S)。突变后Eag I内切酶位点消失。家系中健康成员和50名正常人均未发现该突变。结论 FBN1基因新突变G640A(G214S)是该家系单纯性晶状体异位的致病基因突变。（中华眼科杂志,2004,40：828-831)     

先天性视网膜劈裂症基因突变的分析研究

目的 研究中国先天性视网膜劈裂症（XLRS）患者的基因突变，为患者及亲属提供基因诊断及遗传咨询。 方法 采用聚合酶链反应（PCR）方法，对12个XLRS家系29位男性患者及女性携带者和100名正常对照者的XLRS1基因的6个外显子各片段进行扩增，应用单链构像多态性（SSCP）分析, 对PCR产物进行基因突变筛查，并对发现异常泳动带的PCR产物进行DNA测序, 以明确突变位点及突变类型。 结果 12个XLRS家系检出11种不同的XLRS1致病基因突变，其中，第一外显子碱基缺失致移码突变1种: c.22delT（L9CfsX20）；1种碱基缺失致无义突变（Trp163X）；1种剪接位点突变(c.52+2 T→C; IVS1+2T to C)； 8种碱基替换导致错义突变（Ser73Pro、Arg102Gln、Asp145His、Arg156Gly、Arg200Cys、Arg209His、Arg213Gln、Cys223Arg)。对照者未检测到基因突变。新发现4种基因突变，即：移码突变（L9CfsX20），位于外显子5的Asp145His、Arg156Gly、Trp163X突变；一种新发现的非疾病相关多态性（NSP)：即位于第6外显子的 c.576C→T (Pro192Pro)改变。 结论 12个家系发现11种不同的XLRS1致病基因突变，XLRS1基因突变是导致中国XLRS症的原因。基因突变检测可以为患者及亲属提供基因诊断及家系遗传指导。 (中华眼底病杂志, 2006, 22: 77-81)     

卵黄样黄斑营养不良一家系的BEST-1基因突变分析

目的：通过分子遗传学分析,确定中国东北地区一个先天性卵黄样黄斑营养不良家系在BEST-1基因的突变位点。方法： 采集一先天性卵黄样黄斑营养不良家系2例患者及5例健康成员和100个正常对照者的外周静脉血,提取基因组DNA。应用聚合酶链反应（PCR）扩增BEST-1基因的10个编码外显子,直接测序确定致病的基因突变,并与100名正常对照者的基因筛查结果进行比较。结果：直接测序后发现该先天性卵黄样黄斑营养不良家系BEST-1基因的外显子中,未发现任何突变。结论：BEST-1基因的外显子不存在该先天性卵黄样黄斑营养不良家系的致病突变。     

我国东北地区两家系原发性开角型青光眼的OPTN基因新突变研究

目的 研究我国东北地区两家系原发性开角型青光眼(POAG)的致病基因并确定其基因突变位点.方法 病例对照实验.对两家系POAG患者进行临床研究和系谱分析.采集L家系6例患者和6例健康成员与C家系4例患者和4例健康成员的静脉血,提取基因组DNA.通过连锁分析,确定致病基因的染色体位点后,应用聚合酶链反应(PCR)扩增OPTN基因外显子,直接测序确定致病的基因突变位点.结果 L家系POAG患者的OPTN基因第10外显子发生错义突变,1274 位点AAA变为GAA,对应的赖氨酸替换为谷氨酸(Lys322Glu).L家系中健康成员、C家系全部成员及87名正常人均未发现该位点突变.结论 OPTN基因新突变(Lys322Glu)是L家系POAG的致病基因.     

先天性无虹膜症家系的基因突变位点研究

目的探讨先天性无虹膜症家系的基因突变位点。方法抽取家系成员的外周血2~5ml,提取DNA;先合成2个多态性微卫星遗传标记(D11S904和D11S935)的引物进行聚合酶链反应(PCR),PCR产物变性后用变性聚丙烯酰胺(PAGE)胶分离,根据带型和家系成员间的关系进行单体型连锁分析,判断家系无虹膜表型是否与PAX6基因相关;PCR扩增PAX6基因的所有外显子,所有PCR产物分别进行单链构象多态性(SSCP)分析,通过患者与正常人带型的差异确定突变发生的外显子,对有差异SSCP带型的PCR产物进行直接DNA测序,找到突变位点。结果该家系先天性无虹膜表型明显与PAX6基因连锁;SSCP分析PAX6基因第9外显子PCR产物,显示患者均有异常带型出现,而家系正常人均无此异常带;测序结果显示突变位点为PAX6基因第9外显子c1080核苷酸C突变为T,使编码精氨酸的密码子突变为终止密码子。结论PAX6基因突变可导致先天性无虹膜。     

陕西省两个原发性开角型青光眼家系MYOC基因突变的研究

目的:研究陕西省两个原发性开角型青光眼家系MYOC基因突变情况。方法:分析陕西省两个原发性开角型青光眼家系。从先证者、家族成员及正常对照者外周静脉血中提取基因组DNA;根据MYOC基因编码序列合成7对特异性引物;应用PCR扩增MYOC基因3个外显子序列,DNA测序法双向测序筛选突变位点。结果:家系1中并未发现MYOC基因编码序列的突变位点;家系2中三个患者MYOC基因均存在异常(c.1021T>C杂合突变),导致myocilin蛋白第341位氨基酸由丝氨酸(S)转变为脯氨酸(P)即Ser341Pro错义突变,该家系正常成员及100例对照者中均未发现此突变。结论:MYOC基因Ser341Pro突变可能为家系2原发性开角型青光眼的致病原因。     

先天性眼外肌纤维化ARIX基因多态性研究

目的 分析两个先天性眼外肌纤维化(congenital fibrosis of the extrapcular muscles,CFEOM)家系的临床表型,探讨家系ARIX基因多态性及其意义.方法 对两个CFEOM家系中所有成员共13人进行详细的临床检查,确定患者和正常人.提取DNA,进行PCR扩增,扩增产物进行纯化、DNA测序鉴定,测序结果与GenBank中人ARlX基因序列进行同源性比较.结果 两个家系的遗传方式均是常染色体隐性遗传,两个家系中共8例患者均表现为典型的CFEOM特征.家系I中3例患者均在ARIX基因外显子1出现同义突变156C＞T,在外显子2出现116G＞A,也为同义突变;家系Ⅱ中5例患者在ARIX基因外显子2发生两处突变,即21G＞A和116G＞A,其中116G＞A为同义突变;两家系中正常人均无上述改变.结论 此两家系均属于CFEOM2型,ARIX基因突变可能是导致该两家系致病的分子基础.     

一个CRYAA基因突变先天性白内障家系

目的研究一个四代常染色体隐性遗传性先天性白内障家系的致病基因。方法调查研究。采集一个先天性白内障家系中3例患者和1例表型正常者的外周静脉血各5 ml,收集100例正常人外周静脉血各5 ml作为对照,提取所有参与者基因组DNA。选择与先天性白内障发生相关的八个致病基因（CRYAA、CRYAB、CRYBA1、CRYGC、CRYGD、CRYGS、GJA3、GJA8）作为候选基因,进行聚合酶链反应扩增候选基因的外显子及毗邻内含子。扩增产物进行直接测序,测序结果与GeneBank中序列进行BLAST比对分析,寻找突变位点。结果该家系中先证者及患者均在CRYAA基因第1外显子发生c.160 C>T杂合突变,导致其编码的晶状体蛋白第54位精氨酸变为半胱氨酸（p.R54C）。该家系中参与研究的1名表型正常者和100名正常对照者无此基因突变。结论CRYAA基因 c.160 C>T（p.R54C）突变是导致该先天性白内障家系致病的主要原因。     

一个新的GJA8突变导致一家系遗传性白内障

目的鉴定一个新的常染色体显性遗传性白内障家系的致病性基因突变。方法在前期对本家系基因定位研究的基础上,通过对GJA8基因测序鉴定致病基因及酶切电泳验证突变。结果对缝隙连接蛋白50(connexin50,CX50;编码为GJA8)基因DNA序列分析鉴定显示其第2个外显子的773位核苷酸上C到T的杂和错义突变,引起其蛋白产物258位丝氨酸被苯丙氨酸替代。结论本研究在一遗传性白内障家系发现并鉴定了一个新的GJA8错义突变(S258F),并认为其与导致该家系常染色体显性遗传性白内障发病有关。     

Novel frameshift mutation in NYX gene in a Russian family with complete congenital stationary night blindness

ABSTRACT

Background: The complete form of X-linked congenital stationary night blindness (CSNB1A) is a very rare genetic disease caused by mutation in the NYX gene. CSNB1A-associated several mutations in the NYX gene have been reported earlier.

Methods: In this case report, we have clinically diagnosed and genetically confirmed a novel mutation associated with CSNB1A in four members of a Russian family. Two male siblings from a family of four siblings (two girls, two boys) with non-progressive stable night blindness since early childhood and high myopia underwent - visual acuity test, perimetry, biomicroscopy, OCT, ophthalmoscopy, electroretinography, color vision Hue test, NGS based whole exome analysis and Sanger sequencing for clinical characterization and genetic confirmation of CSNB.

Results: The members are clinically diagnosed and genetically confirmed with CSNB1A. All the patients had a novel frameshift mutation in the NYX gene (c.283delC, p.His95fs, NM_022567.2) that is found to segregate in X-linked manner

Conclusions: This is probably the first case report with a novel mutation from Russia associated with CSNB1A.     

Novel TRPM1 mutations in two Chinese families with early-onset high myopia, with or without complete congenital stationary night blindness

AIM: To investigate the relationship between high myopia [with or without complete congenital stationary night blindness (CSNB1)] and TRPM1 and NYX. METHODS: Two unrelated families with early-onset high myopia (eoHM) and 96 normal controls were recruited. Sanger sequencing or clone sequencing were used for mutation screening. Further analyses of the available family members and the 96 normal controls were subsequently conducted to obtain additional evidence of the pathogenicity of these variants. The initial diagnosis of the probands was eoHM. We performed a further comprehensive examination of the available family members after mutations were detected in TRPM1 or NYX. RESULTS: Two novel compound heterozygous mutations in TRPM1 were detected in the recruited families. The proband in family A with eoHM carried a c.2594C>T missense mutation in exon 19 and a c.669+3_669+6delAAGT splicing mutation, which was co-segregated with CSNB1 in this family. A patient in family B with a compound heterozygous missense mutation (c.3262G>A and c.3250T>C) was detected. No mutations were found in NYX. These two identified compound heterozygous mutations were not found in the 96 normal controls. After further examination of the family members, the patients in family A could be diagnosed as eoHM with CSNB1. However due to the limited clinic data, the patient in family B cloud not clearly diagnosed as CSNB1. CONCLUSION: This study has expanded the mutation spectrum of TRPM1 for CSNB1 and additional studies are needed to elucidate the association between isolated high myopia and TRPM1 and NYX.     

Establishment of the concept of new clinical entities--complete and incomplete form of congenital stationary night blindness

I summarized our long-term study to prove that the complete and incomplete types of congenital stationary night blindness (CSNB) are different clinical entities and that the latter is a newly identified disease which has never been reported in the past. CSNB with normal fundi and negative electroretinogram (ERG) showing selective reduction of the b-wave was previously known as the "Schubert-Bornschein type". For the sake of convenience, we classified the disease into two types according to the absence or the presence of rod function: complete CSNB and incomplete CSNB. The hereditary mode of the former is X-linked recessive and autosomal recessive, while that of the latter is X-linked recessive. They are never found together in a single family. We found several additional differences between the two types, including ERG oscillatory potentials, cone mediated ERG, and refractive errors, all leading us to hypothesize that the two types are not variants of a single disease but are the sum of two different clinical entities. Our hypothesis has recently been proven true by molecular genetical analysis. Namely, the mutated gene in X-linked recessive complete CSNB was found in the nyctalopin (NYX) gene, while that in incomplete CSNB was found in the calcium channel (CANCA1F) gene which encodes the retina-specific calcium channel alpha 1-subunit. These results proved that complete and incomplete CSNB are different clinical entities and that the latter is the first disease of the eye which discloses mutation of this region. We classified 90 patients to include 49 complete and 41 incomplete types. Fifteen incomplete CSNB patients underwent gene analysis and they all showed mutation of the CACNA1F gene. We also examined for gene mutation in several patients who had progressive retinal disease and negative ERG and found two siblings with CANA1F gene mutation. This finding indicates that the mutation of the CACNA1F gene can also cause progressive retinal disease in addition to incomplete CSNB. Gene analysis of 11 patients with complete CSNB was performed and 6 revealed mutation of the NYX gene. The remaining 5 patients showed neither NYX nor CACNA1F gene mutation, suggesting they are of autosomal recessive complete CSNB where gene mutation has not been identified. The comparison of our phenotype and genotype diagnosis indicated that a precise ERG analysis can provide correct differentiation between complete and incomplete types. Other clinical findings include moderately low visual acuity in both types, high or moderate myopia in complete CSNB, and wide distribution from myopia to hyperopia in incomplete CSNB. Pathophysiology studies using clinical patients and animal models suggested that complete CSNB has a complete defect of the ON-bipolar cells or their synapses in the rod and cone visual pathways, leaving the OFF pathway intact (OFF-retina). On the other hand, the incomplete CSNB has an incomplete defect of the ON and OFF bipolar cells or their synapses in the rod and cone visual pathways. The macular function is relatively well preserved in both types, which was shown by focal macular ERG. The incomplete CSNB patients seldom complain of night blindness, which causes us to overlook this disease because we then tend not to perform ERG testing. This disease is not so rare and clinicians should be more aware of its existence. The incomplete CSNB is a new hereditary retinal disease detected by Japanese investigators just like the Oguchi disease, and it has much unknown pathophysiology which needs to be identified in the future. Since the namings of complete and incomplete CSNB may be misunderstood as indicating functional classification of one disease, it has been proposed internationally to change the name "complete type" to CSNB1 and that of "incomplete type" to CSNB2.     

Genotype-phenotype correlation in British families with X linked congenital stationary night blindness

AIM: To correlate the phenotype of X linked congenital stationary night blindness (CSNBX) with genotype. METHODS: 11 CSNB families were diagnosed with the X linked form of the disease by clinical evaluation and mutation detection in either the NYX or CACNA1F gene. Phenotype of the CSNBX patients was defined by clinical examination, psychophysical, and standardised electrophysiological testing. RESULTS: Comprehensive mutation screening identified NYX gene mutations in eight families and CACNA1F gene mutations in three families. Electrophysiological and psychophysical evidence of a functioning but impaired rod system was present in subjects from each genotype group, although the responses tended to be more severely affected in subjects with NYX gene mutations. Scotopic oscillatory potentials were absent in all subjects with NYX gene mutations while subnormal OFF responses were specific to subjects with CACNA1F gene mutations. CONCLUSIONS: NYX gene mutations were a more frequent cause of CSNBX than CACNA1F gene mutations in the 11 British families studied. As evidence of a functioning rod system was identified in the majority of subjects tested, the clinical phenotypes "complete" and "incomplete" do not correlate with genotype. Instead, electrophysiological indicators of inner retinal function, specifically the characteristics of scotopic oscillatory potentials, 30 Hz flicker and the OFF response, may prove more discriminatory.     

A novel CACNA1F mutation in a french family with the incomplete type of X-linked congenital stationary night blindness

PURPOSE: To describe a French family with the incomplete type of X-linked congenital stationary night blindness (CSNB2) associated with a novel mutation in the retina-specific calcium channel alpha(1) subunit gene (CACNA1F). DESIGN: Interventional case report. METHODS: Two family members with a history of nonprogressive night blindness and subnormal visual acuity were clinically examined and the genotype determined by molecular genetic analysis. RESULT: Both patients had clinical manifestations characteristic of CSNB2. Electrophysiologically, we found a predominant reduction of the ERG B-wave in the maximal response. Both rod and cone function were subnormal, with the latter tending to be more attenuated. We identified a C deletion at nucleotide position 4548, resulting in a frameshift with a predicted premature termination at codon 1524. CONCLUSIONS: The clinical and genetic study of a novel mutation in the CACNA1F gene adds further support to the contention that CSNB2 represents a genetically distinct retinal disorder of a calcium channel.     

Molecular genetic study of congenital stationary night blindness

PURPOSE: Molecular genetic study was conducted on patients with fundus albipunctatus, incomplete and complete types of congenital stationary night blindness(CSNB), and Oguchi disease. RESULTS: Mutations in the RDH5 gene were identified in all 10 patients with typical clinical features of fundus albipunctatus. Mutations in the gene were also detected in patients with fundus albipunctatus associated with cone dystrophy, and it was supposed that mutations of the gene cause progressive retinal dystrophy as well as fundus albipunctatus. Mutations in the CACNA1F gene were identified in all 15 patients with typical clinical features of incomplete CSNB. We found that some cases with incomplete CSNB were associated with retinal degeneration or optic atrophy with progressive impairment of vision. We detected mutations in the NYX gene in about half of the cases with complete CSNB. Molecular examination was useful to determine the exact hereditary pattern. We examined the arrestin gene and the rhodopsin kinase gene in 5 unrelated patients with Oguchi disease, and found arrestin gene mutations in 4 of them and a rhodopsin kinase gene mutation in the fifth patient. CONCLUSIONS: We confirmed that fundus albipunctatus, incomplete CSNB, complete CSNB, and Oguchi disease were associated with mutations in the RDH5, CACNA1F, NYX, arrestin or rhodopsin kinase genes, respectively, in Japanese patients. Molecular analysis made it possible to diagnose patients with atypical phenotype and to obtain novel information about phenotypic variation.     

Infantile and childhood retinal blindness: a molecular perspective (The Franceschetti Lecture)

Much progress has been made in the past five years in the understanding of Leber congenital amaurosis (LCA) and allied early-onset retinal dystrophies, various forms of stationary sensory retinal blindness, and genes that are involved in the development of the retina. Uncomplicated Leber congenital amaurosis has been associated with mutations of six genes: GUCY2D (encoding RetGC-1) at 17p13.1, RPE65 at 1q31, CRX at 19q13.3, AIPLI at 17p13.1, CRB1 at 1q31-3, and RPGRIP at 14q11. A similar early-onset severe retinal degeneration phenotype has been associated with mutation of TULP1 at 6p21.3. Leber appreciated that the condition he described merged with the phenotypes of early childhood-onset severe retinal degenerations. This insight has been confirmed at the molecular level for mutations of GUCY2D, RPE65, CRX, AIPL1, and CRB1, which cause not only LCA, but also early-childhood and even adult-onset retinal degenerations. This paper reviews the new finding of LCA from mutations of CRB1 and discusses the molecular basis of X-linked blue monochromacy, autosomal recessive congenital achromatopsia from mutations of the genes for ACHM2 (CNGA3) and ACHM3 (CNGB3), X-linked congenital stationary night blindness (CSNB) from mutations of CACNA1F (incomplete CSNB) and NYX (complete CSNB), and the enhanced S-cone syndrome from mutation of the developmental gene, NR2E3 at 15q23, which appears to regulate the development of M- and L-cones from S-cones. These discoveries have opened new areas of cellular and developmental biology for future research into the causes of retinal blindness.     

Clinical and genetic studies of an autosomal dominant cone-rod dystrophy with features of Stargardt disease

Much progress has been made in the past five years in the understanding of Leber congenital amaurosis (LCA) and allied early-onset retinal dystrophies, various forms of stationary sensory retinal blindness, and genes that are involved in the development of the retina. Uncomplicated Leber congenital amaurosis has been associated with mutations of six genes: GUCY2D (encoding RetGC-1) at 17p13.1, RPE65 at 1q31, CRX at 19q13.3, AIPLI at 17p13.1, CRB1 at 1q31-3, and RPGRIP at 14q11. A similar early-onset severe retinal degeneration phenotype has been associated with mutation of TULP1 at 6p21.3. Leber appreciated that the condition he described merged with the phenotypes of early childhood-onset severe retinal degenerations. This insight has been confirmed at the molecular level for mutations of GUCY2D , RPE65 , CRX , AIPL1 , and CRB1 , which cause not only LCA, but also early-childhood and even adult-onset retinal degenerations. This paper reviews the new finding of LCA from mutations of CRB1 and discusses the molecular basis of X-linked blue monochromacy, autosomal recessive congenital achromatopsia from mutations of the genes for ACHM2 ( CNGA3 ) and ACHM3 ( CNGB3 ), X-linked congenital stationary night blindness (CSNB) from mutations of CACNA1F (incomplete CSNB) and NYX (complete CSNB), and the enhanced S-cone syndrome from mutation of the developmental gene, NR2E3 at 15q23, which appears to regulate the development of M- and L-cones from S-cones. These discoveries have opened new areas of cellular and developmental biology for future research into the causes of retinal blindness.     

Clinical manifestations of a unique X-linked retinal disorder in a large New Zealand family with a novel mutation in CACNA1F, the gene responsible for CSNB2

PURPOSE: To describe the phenotype in a New Zealand family with an unusual severe X-linked retinal disorder with a novel I745T mutation in CACNA1F, the gene responsible for incomplete congenital stationary night blindness (CSNB2). METHODS: Members of the family tree were invited for clinical, psychophysical and electrodiagnostic evaluation. RESULTS: Male family members had severe non-progressive visual impairment, abnormal colour vision, congenital nystagmus, hyperopia and normal fundi. Some were intellectually disabled. Female family members had congenital nystagmus and decreased visual acuity frequently associated with high myopia. Electroretinograms (ERG) identified reduced rod and cone responses with negative waveform in male and female family members, with atypical features for CSNB2. CONCLUSIONS: Although there were similarities to CSNB2, distinctive features in male family members included severity of phenotype, and association of intellectual disability. Moreover, all female heterozygotes had clinical and ERG abnormalities. CACNA1F encodes the Ca(v)1.4 alpha1 subunit of a voltage-gated calcium channel, which may mediate neurotransmitter release from photoreceptors. Molecular analyses, reported separately, identified a novel I745T CACNA1F mutation that was associated in vitro with major alterations in gating and kinetics of the Ca(v)1.4 channel. It is speculated that the unique phenotype described in this family may reflect similarly altered function of Ca(v)1.4 channel activity in vivo.     

Phenotypic expression of the complete type of X-linked congenital stationary night blindness in patients with different mutations in the <Emphasis Type="Italic">NYX</Emphasis> gene

PURPOSE: To describe the clinical phenotype of the complete type of X-linked congenital stationary night blindness (CSNB1) with different types of mutations in the NYX gene. METHODS: The clinical and genetic data from 18 male patients with eight different mutations from two ophthalmological institutes were reviewed. The variability in refractive error, reduced visual acuity and full-field electroretinogram (ERG) recordings was examined. RESULTS: Parameters were quantitatively analyzed based on the classification of mutations according to their predicted effect on protein structure and function. CSNB1 patients with mutations changing structurally conserved residues ( n=12) tended to have a lower degree of myopia than patients with mutations of non-conserved residues ( n=6). Visual acuity loss and the 30 Hz flicker ERG recordings were similar in the two groups. Values for the b/a amplitude ratio tended to be clustered in patients carrying the same mutation. Refractive error and the b/a amplitude ratio were highly correlated between the two eyes of an individual. CONCLUSIONS: These data suggest correlations between phenotypic expression in CSNB1 and individual genotypes as well as class types of mutations based on the extent of structural amino acid conservation. A high inter-eye correlation suggests that other genetic or environmental factors, rather than chance, play a part in determining the phenotypic diversity in CSNB1.