CAJ | 학술논문

目的研究一个4代常染色体显性遗传先天性核性白内障伴小角膜家系的致病基因.方法实验研究.对12例家系成员(6例患者,6例非患者)进行眼部检查并采集静脉血,提取基因组DNA.在已知的与先天性白内障伴小角膜相关致病基因附近选择微卫星标记,进行聚合酶链反应扩增-变性聚丙烯酰胺凝胶电泳,并进行基因型分析和连锁分析.对连锁区域内候选基因的外显子、外显子和内含子交界区进行测序.限制性内切酶ApaL Ⅰ法在全部家系成员和正常人群中验证突变.结果该家系患者表型为先天性核性白内障伴小角膜;在染色体21q22.3区域的D21S1885和D21S1890两个标记,家系患者均有共享基因型,并且两点连锁分析Lod值为2.11,提示该位点与家系致病基因连锁;对此区域内候选基因CRYAA测序发现cDNA序列第34位碱基存在C＞T杂合突变(c.34C＞T),导致其编码肽链第12位精氨酸变为半胱氨酸(p.R12C).ApaL Ⅰ酶切验证家系患者均携带c.34C＞T突变,家系中及对照正常个体均不携带此突变.结论 CRYAA的p.R12C突变可能是该先天性白内障伴小角膜家系发病的遗传基础.
목적 연구일개4대상염색체현성유전선천성핵성백내장반소각막가계적치병기인.방법 실험연구.대12례가계성원(6례환자,6례비환자)진행안부검사병채집정맥혈,제취기인조DNA.재이지적여선천성백내장반소각막상관치병기인부근선택미위성표기,진행취합매련반응확증-변성취병희선알응효전영,병진행기인형분석화련쇄분석.대련쇄구역내후선기인적외현자、외현자화내함자교계구진행측서.한제성내절매ApaL Ⅰ법재전부가계성원화정상인군중험증돌변.결과 해가계환자표형위선천성핵성백내장반소각막;재염색체21q22.3구역적D21S1885화D21S1890량개표기,가계환자균유공향기인형,병차량점련쇄분석Lod치위2.11,제시해위점여가계치병기인련쇄;대차구역내후선기인CRYAA측서발현cDNA서렬제34위감기존재C＞T잡합돌변(c.34C＞T),도치기편마태련제12위정안산변위반광안산(p.R12C).ApaL Ⅰ매절험증가계환자균휴대c.34C＞T돌변,가계중급대조정상개체균불휴대차돌변.결론 CRYAA적p.R12C돌변가능시해선천성백내장반소각막가계발병적유전기출.
Objective To identify the gene mutation in a four-generation Chinese family with autosomal dominant congenital cataract associated with microcornea. Methods Experimental research.Twelve members in this family (including six affected and six unaffected individuals) were enrolled into this study. They underwent full ophthalmological and clinical examinations to rule out any concomitant disorders.Blood samples were collected and genomic DNA was extracted. Microsatellite markers near the reported loci,which are associated with congenital cataract and microcornea were selected and amplified from DNA samples using polymerase chain reaction. Linkage analysis was performed. The exons and exon/intron junction of candidate gene in the related chromosome were sequenced. The product of the first exon was digested by ApaL Ⅰ restriction enzyme to certify the mutation. Results The phenotype studied in this family was nuclear cataract accompanied with microcornea. At markers D21S1885 and D21S1890 near the locus 21q22. 3, the affected members had the same allele, but the unaffected did not. The Lod scores were 2. 11in both markers, indicating that this locus were linked to the congenital cataract in this family. DNA sequencing of candidate gene CRYAA showed a heterozygous mutation c. 34C ＞ T in exon 1, which led to condon 12 in peptide chain encoding arginine substituted by cysteine. ApaL Ⅰ enzyme digestion certified that all of the affected members had the same mutation c. 34C ＞T, but the unaffected and normal individuals did not. Conclusion Mutation (p. R12C) of CRYAA is the genetic change that causes the occurrence of congenital cataract with microcornea in this family.