小儿视锥细胞与视锥杆细胞营养不良的临床 特点与候选基因突变分析

目的分析小儿视锥细胞和视锥杆细胞营养不良的临床特点及其候选基因变异情况。方法连续收集分析18例年龄4个月至8岁的视锥细胞和视锥杆细胞营养不良先证者的临床资料。应用聚合酶链反应异源双链单链构像多态法分析锥杆同源异形盒基因（cone-rod homeobox gene,CRX）全部3个外显子、GUCY2D基因（retinal-specific guanylate cyclase gene）外显子2和8,寻找可能的变异。结果18例患儿因家人发现其有明显视觉障碍来诊。 其中13例有眼球震颤,8例有畏光,7例有轻微、不典型眼底改变。11例眼底正常。4例可测 定视力者视力均低于0.3,14例小于3岁者无法测定视力。视锥细胞营养不良与视锥杆细胞营养不良的临床症状和眼部表现相互重叠。均未发现CRX基因和GUCY2D基因突变。结论小儿视锥细胞和视锥杆细胞营养不良视觉障碍明显,眼球震颤较多见。多数眼底正常,少数有眼底改变但不典型。本组病例可能与CRX基因和GUCY2D基因外显子2、8突变无关。(中华眼底病杂志,2001,17:293-295)

Clinical characteristics and candidate gene mutational screening in children with cone and cone-rod dystrophy

Objective To analyze the clinical characteristics and to screen for causative mutations in CRX and GUCY2D genes in children with cone or cone-rod dystrophy. Methods Clinical data and genomic DNA was collected from 18 children with cone or cone-rod dystrophy, aged from 4 months to 8 years. The coding sequence of the cone-rod homeobox (CRX) gene and two exons of the retinal-specific guanylate cyclase GUCY2D gene (exons 2 and 8) were analyzed by using polymerase chain reaction(PCR) and heteroduplex combined with single-strand conformational polymorphism (heteroduplex-SSCP) analysis. Results All of the 18 patients manifested obvious visual impairment. Nystagmus, photophobia and mild ocular fundus changes were found in 13, 8,and 7 cases respectively. Normal fundus was seen in 11 cases. The visual acuity was less than 0.3 in 4 cases and was unable to measure in the other 14 cases because they were too young. Clinical ocular manifestations between cone and cone-rod dystrophy were overlapped. Mutation in the CRX and GUCY2D genes was not detected in the 18 children with cone and cone-rod dystrophy. Conclusion Visual impairment appeared more early and obvious than fundus changes in children with cone or cone-rod dystrophy. Mutation in the CRX gene may not contribute to this series of patients with cone and cone-rod dystrophy.