先天性广泛眼外肌纤维化综合征一家系临床表型及基因连锁定位分析

目的 分析一个先天性广泛眼外肌纤维化综合征(CFEOM)家系的临床表型，并通过连锁分析方法来定位该家系的致病基因。方法 对家系中的所有患者进行临床检查。根据目前已知的两种常染色体显性遗传类型的CFEOM的遗传学位点12p11．2-q12(FEOM1)和16q24(FEOM3)选取微卫星进行连锁分析研究。结果 家系中4名患者具有典型的CFEOM表现。连锁分析显示，微卫星D12S59、D12S1048、D12S1648在所有患者中与疾病呈现共分离现象，其中D12S1048最大Lod值为1．91，而在微卫星D12S61和D12S1090处出现重组，表明该家系的致病基因位于这两个微卫星之间。结论此家系属常染色体显性遗传的CFEOM 1型，其致病基因定位于12p11．2-q12的D12S61和D12S1090之间。     

先天性广泛眼外肌纤维化综合征一家系的连锁分析和候选基因研究

目的探讨先天性广泛眼外肌纤维化综合征(CFEOM)一家系的临床表型特征和致病基因。方法收集CFEOM一家系,对全部患者进行临床检查和全基因组扫描及连锁分析(1inkage analysis),对连锁区域内的候选基因KIf21A进行基因序列分析。结果此家系中4例患者具有典型CFEOM临床表现。连锁分析显示微卫星标记物D12S1648、D12s345、D12S1692、D12S59、D12S1090、D12S2194、D12S1048、D12S1668在家系中与全部患者的疾病表型共分离,并在D12S1090取得最大LOD值(2．12)。KIf21A基因测序未发现突变,仅在外显子21发现一单个碱基多态性改变。结论此家系属常染色体显性遗传CFEOM1型,致病基因定位于染色体带12p11．2-q12微卫星标记物D12S1648和D12S1668之间约4cM的区域。KIF21A基因可能不是此家系的致病基因。(中华眼科杂志,2005,41：594-599)     

先天性眼外肌纤维化一家系致病基因的连锁分析

目的分析一个中国人先天性眼外肌纤维化(congenital fibrosis of extraocularmuscles,CFEOM)家系的临床表型,并通过基因连锁分析的方法对该家系的致病基因进行定位研究。方法收集一个CFEOM家系,对家系所有成员进行详细的临床检查。确定其临床表型及遗传方式后,在位于11号染色体的已知CFEOM基因附近选取微卫星标记物进行连锁分析。运用MILINK软件计算最大优势对数LOD值。结果该家系的遗传方式为常染色体隐性遗传,家系中的5例患者均表现为典型的眼外肌纤维化特征。与该家系连锁的染色体微卫星标记物为D11S4151和D11S1320,其最大的LOD值为1.21。结论此家系为常染色体隐性遗传型CFEOM2型,其致病基因位于11号染色体的D11S4151和D11S1320之间,位于该区间内的已知基因PHOX2A/ARIX的突变可能是导致该家系致病的分子基础。     

常染色体显性视网膜色素变性家系基因定位的研究

目的 对一个常染色体显性视网膜色素变性大家系进行基因定位。方法 收集视网膜色素变性家系,并对该家系成员进行详细眼部检查;抽取外周血3－5ml并提取DNA;采用多个已知遗传标记与该家系致病基因位点进行连锁分析。结果 两点连锁分析结果显示该家系致病基因位点与遗传位标D3S1292连锁,在θ＝0．1时间到最大LOD值2．73。结论 D3S1292位于3号染色体长臂2区1带（3q21),从而将该家系致病基因位点大致定位于3q21附近。同时有文献报道视紫红质基因位点也位于3q染色体上,且与D3S1292邻近,因此该家系的致病基因很可能是视紫红质基因。     

一常染色体显性遗传性白内障家系致病基因的排除性定位

目的对常染色体显性遗传先天性白内障家系进行致病基因的定位研究。方法对4代11例家系成员（6例患者）进行眼部和全身检查,采集静脉血,提取基因组DNA,选取已报道的与遗传性白内障相关位点附近的微卫星标记,PCR扩增后进行基因型分析,用连锁分析进行排除;没有排除的位点,基因外显子测序。结果 35例家系成员中,追溯调查共有10例患者,其中第1代1例,第2代2例,第3代5例,第4代2例。该家系患者表型为完全性白内障;绝大多数位点,患者没有共享基因型;微卫星标记与致病基因间的2点连锁Lod值〈-2,证实这些位点与该家系的致病基因不连锁;有3个多态性标记（D10S1239、D22S286、D22S926）0〈Lod值≤0.6,Lod值虽然不是〈-2,但在家系患者中没有共享等位基因;测序未发现外显子有突变。结论此家系的致病基因不是已报道位点的致病基因,其致病基因有待进一步研究。     

原发性开角型青光眼家系致病基因的定位研究

目的采用候选位点连锁分析的方法对常染色体显性遗传的原发性开角型青光眼（POAG）一家系的致病基因进行定位。方法对重庆一大型POAG家系进行全面遗传学调查和样本采集,以短串联重复序列（STR）为分子遗传学标记,首先采用候选位点连锁分析的方法对该家系进行MYOC、OPTN、WDR36和CYP1B1基因的筛查定位,然后在阳性位点D2S2259上下游加密STR进一步行精细定位及单体型分析。结果由D2S2369、D2S2352、D2S378和D2S337所确定的染色体区域与该家系的致病基因紧密连锁（θ=0.00时,LODs分别为：D2S2369=4.584;D2S2352=2.992;D2S378=6.238;D2S337=4.892）。该区域位于人类染色体2p15～p16.3,长约7cM/7.5Mb,其中共有12个基因在眼部表达。结论研究与2007年Suriyapperuma SP等对7个欧裔成人型POAG家系的定位区域一致,且范围更小。     

Avellino角膜营养不良家系致病基因的定位研究

目的：对收集到的一个常染色体显性遗传性Avellino角膜营养不良家系的致病基因进行初步定位。
　　方法：采集家系中所有成员的外周静脉血,从中提取基因组DNA样本。在热点区域内选取微卫星标记进行基因扫描,分别利用LINKAGE软件和CYRILLIC软件进行连锁分析及单体型分析,以确定候选基因所在的染色体区域。
　　结果：该Avellino角膜营养不良家系的连锁分析结果在D5 S396和D5 S393这两个微卫星标记处获得最大优势对数计分(LOD)值,Zmax=3.01(θ=0.00)。单体型分析将致病基因定位于微卫星标记D5 S808和D5 S638之间。
　　结论：该Avellino角膜营养不良家系的致病基因初步定位于染色体5q上的遗传距离约为11.2厘摩( cM)的一段区域内。     

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。     

常染色体显性遗传性先天性白内障一家系致病基因的初步定位

目的 初步定位常染色体显性遗传性先天性白内障(ADCC)一家系的致病基因。方法 收集ADCC一家系资料,在已知先天性白内障致病基因和位点附近,选择合适的短串联重复序列多态性标记(STRP),对ADCC一家系进行连锁分析,使用Mlink软件采用对数优势记分法(LOD)计算LOD值。结果 在STRP中,D17S805、D17S1294及D17S1293与致病基因位点连锁的最大LOD值分别为2．03、2．49及2．22(重组率0=0)。结论 该ADCC家系的致病基因初步定位在第17对染色体上;CRYBA1基因为候选基因。（中华眼科杂志,2004,40：824-827)     

中国人Meesmann角膜营养不良家族KRT12基因突变检测分析

目的探讨中国Meesmann角膜营养不良家系的致病相关基因。方法对一具有3代患者的角膜营养不良家系进行详细的临床遗传学诊断,确定遗传方式与遗传特点,然后对该家系成员包括患者和正常人,进行详细的眼科检查,获得血液标本,提取基因组DNA。对已知基因KRT12、KRT3周围标记物D17S800、D17S930、D12S390、D12S96分别进行基因扫描,然后进行连锁分析,计算最大对数优势记分值。对连锁区域内已知基因所有外显子聚合酶链反应（PCR）扩增产物进行直接测序。结果该家系角膜营养不良的遗传方式为常染色体显性遗传,临床诊断为Meesmann角膜营养不良,连锁的染色体微卫星标记物为D17S800和D17S930,分值为2．41（θ=0．00）,与KRT12基因连锁。对全部8个外显子测序后发现该基因第一外显子（exon 1）第419碱基突变（T419A）,其编码的亮氨酸突变为组氨酸（L132H）。结论KRT12基因突变（T419A,L132H）可能是该中国人家系Meesmann角膜营养不良家族发病的分子基础。     

Evidence of genetic heterogeneity in autosomal recessive congenital fibrosis of the extraocular muscles

PURPOSE: Autosomal recessive congenital fibrosis of the extraocular muscles (CFEOM2) has been described in families from Saudi Arabia. Affected individuals have ptosis and exotropic ophthalmoplegia, and their disease has been mapped to chromosome 11q13. Here, we describe the phenotypic findings in a similarly affected Yemenite family and analyze the family for linkage to the CFEOM2 locus, as well as to the autosomal dominant CFEOM1 and CFEOM3 loci on chromosomes 12cen and 16q24, respectively. METHODS: The family was ascertained through two affected daughters. There are four unaffected siblings, and the parents are consanguineous. Each family member was examined, and linkage analysis was performed using markers from the CFEOM1, CFEOM2, and CFEOM3 loci. RESULTS: Both affected daughters have congenital bilateral ophthalmoplegia. The 15-month-old proband has restrictive exotropia. She fixates with either eye in abduction and with a compensatory head turn to the opposite side. Her 4-year-old sister has a small exotropia and severely limited eye movements. All other family members have normal ophthalmologic examinations. Genetic analysis excluded linkage of the family's disease to the CFEOM2 and CFEOM3 loci. A lod score of 2.0 (the maximum possible, given the family size and structure), was obtained at the CFEOM1 locus, and the alleles reduced to homozygosity in both affected daughters and none of the other children. CONCLUSIONS: These data establish that there is genetic heterogeneity in autosomal recessive CFEOM and suggest that this second recessive locus may be allelic to the autosomal dominant CFEOM1 locus at 12cen.     

Mutation analysis of KIF21A in congenital fibrosis of the extraocular muscles (CFEOM) patients

PURPOSE: CFEOM type 1 refers to a group of congenital eye movement disorders that is characterized by nonprogressive ophthalmoplegia affecting all the extraocular muscles. Individuals with the classic form of CFEOM are born with bilateral ptosis, infraducted eyes, and impossibility to raise their eyes above midline. This phenotype is often inherited as an autosomal dominant trait. CFEOM1 maps to the FEOM1 locus on chromosome 12 and is the consequence of mutations in the KIF21A gene. We analyzed three families and one sporadic case for potential genetic heterogeneity. METHODS: Blood samples were collected from members of three families (Swiss, Turkish, and French origin) and one sporadic case (Iranian origin). In families, haplotype was tested for linkage to the autosomal dominant CFEOM1 locus on chromosome 12. Linkage studies were conducted using 2 polymorphic DNA microsatellite markers, D12S331 and D12S1048. Mutation analysis was performed by PCR amplification and bidirectional direct sequencing. RESULTS: Haplotype analysis was compatible with linkage to the CFEOM1 locus in all affected members. Mutation analysis revealed the classical mutation R954W in all affected cases, including the sporadic case, regardless of their ethnic origin. The c.2860C>T base change was not observed in 100 individuals from various ethnic origins. CONCLUSIONS: As reported, the classical c.2860C>T mutation represents a hotspot for mutation in various ethnic groups, including Swiss, Turkish, French, and Iranian patients. Sporadic cases are often due to neo-mutations as in our case. Mutation analysis is important, especially in sporadic cases, to correctly evaluate recurrence and transmission risks.     

Clinical and genetic analysis of a family with X-linked congenital nystagmus (NYS1)

Purpose: CFEOM type 1 refers to a group of congenital eye movement disorders that is characterized by nonprogressive ophthalmoplegia affecting all the extraocular muscles. Individuals with the classic form of CFEOM are born with bilateral ptosis, infraducted eyes, and impossibility to raise their eyes above midline. This phenotype is often inherited as an autosomal dominant trait. CFEOM1 maps to the FEOM1 locus on chromosome 12 and is the consequence of mutations in the KIF21A gene. We analyzed three families and one sproradic case for potential genetic heterogeneity. Methods: Blood samples were collected from members of three families (Swiss, Turkish, and French origin) and one sporadic case (Iranian origin). In families, haplotype was tested for linkage to the autosomal dominant CFEOM1 locus on chromosome 12. Linkage studies were conducted using 2 polymorphic DNA microsatellite markers, D12S331 and D12S1048. Mutation analysis was performed by PCR amplification and bidirectional direct sequencing. Results: Haplotype analysis was compatible with linkage to the CFEOM1 locus in all affected members. Mutation analysis revealed the classical mutation R954W in all affected cases, including the sporadic case, regardless of their ethnic origin. The c.2860C&;gt;T base change was not observed in 100 individuals from various ethnic origins. Conclusions: As reported, the classical c.2860C&;gt;T mutation represents a hotspot for mutation in various ethnic groups, including Swiss, Turkish, French, and Iranian patients. Sporadic cases are often due to neo-mutations as in our case. Mutation analysis is important, especially in sporadic cases, to correctly evaluate recurrence and transmission risks.     

CFEOM3: a new extraocular congenital fibrosis syndrome that maps to 16q24.2-q24.3.

PURPOSE: To define the clinical characteristics and determine the gene localization for a previously undescribed form of congenital fibrosis of the extraocular muscles (CFEOM), referred to as CFEOM type 3 (CFEOM3). METHODS: A large family with CFEOM was identified, and participating individuals underwent ophthalmologic examination and donated blood for genetic analysis. The family's disorder was tested for linkage to the known CFEOM loci, followed by a genome-wide search and linkage refinement using polymorphic DNA markers. RESULTS: Thirty-eight members of this Canadian family participated in the study. Affected individuals are born with a nonprogressive eye movement disorder characterized by variable expression of ptosis and restrictive external ophthalmoplegia. Severely affected individuals have ptosis, primary gaze fixed in a hypo- and exotropic position, and marked restriction of eye movement bilaterally. Mildly affected individuals have normally positioned globes with a limitation of vertical gaze. Moderately affected individuals have asymmetrical involvement with one eye severely and one eye mildly affected. The disorder is autosomal dominant with variable expression and probable incomplete penetrance. Genetic analysis reveals linkage to markers on 16q24.2q24.3. A maximum lod score of 5.8 occurs at markers D16S3063 and D16S689, and the CFEOM3 disease gene is located within a 5.6-cM region flanked by D16S486 and D16S671. CONCLUSIONS: These data establish that CFEOM3 is a phenotypically variant and genotypically distinct form of CFEOM with linkage to chromosome 16qter. The authors have previously demonstrated that CFEOM1 results from a developmental absence of the superior division of the oculomotor nerve. The authors hypothesize that CFEOM3 results from a defect analogous to, but distinct from CFEOM1.     

A novel locus for autosomal dominant nuclear cataract mapped to chromosome 2p12 in a Pakistani family

PURPOSE: To map the disease locus in a four-generation, consanguineous Pakistani family affected by autosomal dominant congenital nuclear cataract (adNCat). All affected individuals had early onset of bilateral nuclear cataract. METHODS: Genomic DNA from family members was typed for alleles at more than 300 known polymorphic genetic markers by polymerase chain reaction. The lod scores were calculated by using two-point linkage analysis of the genotyping data. RESULTS: The maximum lod score, 4.05, was obtained for the marker D2S2333. Proximal and distal crossovers were observed with markers D2S286 and D2S1790, respectively. These crossovers define the critical disease locus to an interval of approximately 9 centimorgans (cM). CONCLUSIONS: Linkage analysis identified a novel locus for adNCat on chromosome 2p12 in a Pakistani family. A genome database analysis of the target interval is being undertaken to identify candidate gene(s) for the disease.     

A new locus for autosomal dominant cataract on chromosome 12q13

PURPOSE: To map the gene for autosomal dominant cataracts (ADC) in an American white family of European descent. METHODS: Ophthalmic examinations and linkage analyses using a variety of polymorphisms were performed; two-point lod scores calculated. RESULTS: Affected individuals (14 studied) exhibited variable expressivity of embryonal nuclear opacities based on morphology, location within the lens, and density. This ADC locus to 12q13 was mapped on the basis of statistically significantly positive lod scores and no recombinations (theta(m) = theta(f) = 0) with markers D12S368, D12S270, D12S96, D12S359, D12S1586, D12S312, D12S1632, D12S90, and D12S83; assuming full penetrance, a maximum lod score of 4.73 was calculated between the disease locus and D12S90. CONCLUSIONS: The disease in this family represents the first ADC locus on chromosome 12; major intrinsic protein of lens fiber (MIP) is a candidate gene.     

An autosomal dominant bull's-eye macular dystrophy (MCDR2) that maps to the short arm of chromosome 4

PURPOSE: To describe the phenotype of an autosomal dominant macular dystrophy and identify the chromosomal locus. METHODS: Eleven members of a five-generation, nonconsanguineous British family were examined clinically and also underwent automated perimetry, electrodiagnostic testing, fundus fluorescein angiography, and fundus autofluorescence imaging. Blood samples were taken for DNA extraction and linkage analysis was performed. RESULTS: The phenotype is characterized by bull's-eye macular dystrophy first evident in the first or second decade of life. There is mild visual impairment, central scotomata, and electrophysiological testing indicates that most affected individuals have disease confined to the central retina but older subjects have more widespread rod and cone abnormalities, demonstrated by flash ERG. Genetic linkage analysis established linkage to chromosome 4 at p15.2-16.3 with a maximum lod score of 3.03 at a recombination fraction of 0.00 for marker D4S391. The locus for this autosomal dominant macular dystrophy lies between flanking markers D4S3023 and D4S3022, and overlaps the Stargardt 4 locus. CONCLUSIONS: A new locus was identified for a bull's-eye macular dystrophy on the short arm of chromosome 4.