CAJ | 학술논문

背景先天性白内障的致病基因及临床表型具有明显的异质性,通过连锁分析进行基因定位,直接测序法筛选致病基因是目前常用的分析方法.目的对2个先天性珊瑚状白内障家系(CC1和CC2)进行致病基因研究.方法收集确诊为常染色体显性遗传的2个先天性珊瑚状白内障家系17名成员的外周静脉血各5ml,包括11例患者、4名正常成员和2名配偶,提取基因组DNA.选取与已知常染色体显性遗传先天性白内障相关的位点进行基因组扫描,利用微卫星标记物进行PCR扩增并进行序列分析.采用两点法计算LOD值对致病基因进行连锁分析.采用直接测序法对候选致病基因以及3个单核苷酸多态性(SNP)位点(rs2305429,rs2305430,rs2242074)进行序列分析.利用SNP对2个家系的先证者进行单体型分析.结果 CC1和CC2家系中的先证者裂隙灯下均可见双眼晶状体核中央混浊区呈珊瑚状,经两点法计算LOD值,家系CC1在微卫星位点D2S325 获得的最大LOD值为3.28,而CC2家系在D2S325 获得的最大LOD值为1.50,连锁分析结果支持2个家系均与位于2q的候选致病基因CRYGC和CRYGD连锁.基因序列分析发现2个珊瑚状白内障家系均携带CRYGD基因 c.C70A.(p.P23T)突变体,而2个家系中的正常人及100名正常对照则无此基因突变.2个家系先证者携带不同类型的单体型结构.结论 CRYGD基因c.C70A.(p.P23T)突变是导致2个不同祖先来源的先天性珊瑚状白内障家系CC1和CC2致病的主要原因.
배경 선천성백내장적치병기인급림상표형구유명현적이질성,통과련쇄분석진행기인정위,직접측서법사선치병기인시목전상용적분석방법.목적 대2개선천성산호상백내장가계(CC1화CC2)진행치병기인연구.방법 수집학진위상염색체현성유전적2개선천성산호상백내장가계17명성원적외주정맥혈각5ml,포괄11례환자、4명정상성원화2명배우,제취기인조DNA.선취여이지상염색체현성유전선천성백내장상관적위점진행기인조소묘,이용미위성표기물진행PCR확증병진행서렬분석.채용량점법계산LOD치대치병기인진행련쇄분석.채용직접측서법대후선치병기인이급3개단핵감산다태성(SNP)위점(rs2305429,rs2305430,rs2242074)진행서렬분석.이용SNP대2개가계적선증자진행단체형분석.결과 CC1화CC2가계중적선증자렬극등하균가견쌍안정상체핵중앙혼탁구정산호상,경량점법계산LOD치,가계CC1재미위성위점D2S325 획득적최대LOD치위3.28,이CC2가계재D2S325 획득적최대LOD치위1.50,련쇄분석결과지지2개가계균여위우2q적후선치병기인CRYGC화CRYGD련쇄.기인서렬분석발현2개산호상백내장가계균휴대CRYGD기인 c.C70A.(p.P23T)돌변체,이2개가계중적정상인급100명정상대조칙무차기인돌변.2개가계선증자휴대불동류형적단체형결구.결론 CRYGD기인c.C70A.(p.P23T)돌변시도치2개불동조선래원적선천성산호상백내장가계CC1화CC2치병적주요원인.
Background Clinical and genetic heterogeneity of congenital cataract is well substantiated.Researchers often identify disease loci by linkage analysis and screen candidate gene by direct sequencing.Objective This study was to localize and identify the disease-causing genes for two Chinese families with congenital coralliform cataracts.Methods Two Chinese families(CC1 and CC2) with autosomal dominant inheritance congenital coralliform cataracts were ascertained and patients in the families underwent ophthalmological examination.Periphery blood samples were collected and DNA was extracted from 17 subjects including 11 cataract patients and 4 phenotype normal and 2 spouses.A linkage scan of genomic regions containing 25 known candidate genes was performed using 50 polymorphic microsatellite markers on genomic DNA from affected and unaffected family members and LOD scores were calculated.Candidate genes were sequenced and mutations were analyzed.Three single nucleotyde polymorphisms(SNP)(rs2305429,rs2305430,rs2242074) were sequenced and genotyped for the detect of the possibility of a common origin between CC1 and CC2.This study complied with the Declaration of Helsinki and was approved by Ethic Committee of Tianjin Eye Hospital.The informed consent was obtained from subjects and their guardian before the protocol.Results A significant LOD score of 3.28(θ=0) in family CC1 and a maximum LOD score of 1.50(θ=0) in family CC2 were both produced at the microsatellite marker D2S325 linked with CRYGD gene.Sequencing of CRYGD gene showed a heterozygous single base pair change c.70C＞A in exon2,predicting to result in a P23T amino acid change.The haplotypes of two probands in their respective families was quite distinct.Conclusion These results indicate that c.C70A(p.P23T) mutation in CRYGD gene is the underlyingmolecular pathogenesis of the two families with congenital coralliform cataracts,and this mutation occurs independently in these two families rather than descending from a common ancestor.