Pan Zhe, Lu Tingting, Zhang Xiaohui, Dai Hanjun, Yan Weiyu, Bai Fengge, Li Yang
Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, China.
Mol Vis. 2012;18:3013-20. Epub 2012 Dec 14.
To describe the clinical and genetic findings in two Chinese families with retinitis pigmentosa (RP).
Two unrelated families were examined clinically. After informed consent was obtained, genomic DNA was extracted from the venous blood of all participants. Genotyping and haplotyping analysis was performed on the known genetic loci for autosomal dominant retinitis pigmentosa (adRP) with a panel of polymorphic markers in the two families, and then mutation screening of all coding exons of the RHO gene was performed by direct sequencing of PCR-amplified DNA fragments. Whenever substitutions were identified in a patient, restriction fragment length polymorphism analysis was performed on all available family members and on 100 normal controls.
Clinical examination and pedigree analysis revealed two four-generation families (83 and 112) with adRP. A significant two-point linkage odd disequilibrium (LOD) score was generated at marker D3S1292 (Zmax=1.90, θ=0) for family 83 and (Zmax=2.77, θ=0) for family 112, respectively, and further linkage and haplotype studies confined the disease locus to 3q21-22 where the RHO gene is located. Mutation screening of the RHO gene in the two families revealed a G→C transversion at position 505 (p.A169P) of the cDNA sequence in family 83 and a C→A transversion at position 1040 (p.P347Q) of the cDNA in family 112. The novel p.A169P and recurrent p.P347Q mutations cosegregated with the phenotypes of the two families. Secondary structure prediction suggested that the mutant rhodopsin 169P led to significant secondary structure changes between residues 165 and 169, which may interfere with the correct folding of the transmembrane domain.
Two mutations of the RHO gene were identified in two Chinese families with adRP. Our findings further suggest codon 347 is the mutation hotspot of the RHO.
描述两个患有视网膜色素变性（RP）的中国家庭的临床和基因学发现。
对两个无血缘关系的家庭进行临床检查。在获得知情同意后，从所有参与者的静脉血中提取基因组DNA。使用一组多态性标记对常染色体显性视网膜色素变性（adRP）的已知基因位点进行基因分型和单倍型分析，然后通过对PCR扩增的DNA片段进行直接测序，对RHO基因的所有编码外显子进行突变筛查。每当在患者中鉴定出替换时，对所有可用家庭成员和100名正常对照进行限制性片段长度多态性分析。
临床检查和家系分析揭示了两个患有adRP的四代家庭（83号和112号）。83号家庭在标记D3S1292处产生了显著的两点连锁奇数不平衡（LOD）分数（Zmax = 1.90，θ = 0），112号家庭在该标记处产生了（Zmax = 2.77，θ = 0），进一步的连锁和单倍型研究将疾病位点定位到3q21 - 22，即RHO基因所在的位置。对这两个家庭的RHO基因进行突变筛查，发现83号家庭cDNA序列第505位发生G→C颠换（p.A169P），112号家庭cDNA序列第1040位发生C→A颠换（p.P347Q）。新的p.A169P突变和复发性p.P347Q突变与两个家庭的表型共分离。二级结构预测表明，突变的视紫红质169P导致165至169位残基之间的二级结构发生显著变化，这可能会干扰跨膜结构域的正确折叠。
在两个患有adRP的中国家庭中鉴定出RHO基因的两个突变。我们的发现进一步表明密码子347是RHO基因的突变热点。
