Single nucleotide polymorphisms of the myocilin gene in primary open-angle glaucoma patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect single nucleotide polymorphisms (SNPs) of the myocilin (MYOC) gene and to investigate their associations with primary open-angle glaucoma (POAG).</p><p><b>METHODS</b>One hundred and fifty-seven sporadic patients with POAG and 155 unrelated control subjects without POAG were recruited from staff and visitors to the Prince of Wales Hospital between 1998 and 2000. All study subjects are ethnic Chinese living in Hong Kong. The two populations were matched in frequencies of gender and age. The SNPs of the MYOC gene in POAG patients and control subjects were screened and identified by high throughout conformation sensitive gel electrophoresis and fluorescent labeling automated sequencing. The genotype frequencies of each SNP in the two groups were compared by the Chi2 test or Fisher's exact 2-tailed test.</p><p><b>RESULTS</b>A total of seventeen SNPs were identified from 2172 bp long of the MYOC gene, including all 3 exons and adjacent non-coding regions. The identified SNPs were 1-83G --> A, G12R, P16L, A17S, R46X, R76K, R91X, T123T, D208E, L215P, 730+35A --> G, A260A, I288I, E300K, T353I, Y471C and 1515+73G --> C, respectively. Of these, R91X, E300K and Y471C were found only in POAG patients. A significant difference between POAG patients and control subjects was found in the genotype frequencies of 1515+73G --> C. The frequency of the heterozygote (CG) was 0.6% in POAG patients, significantly less than the 4.5% in control subjects (Fisher's exact 2-tailed test, P=0.036, OR=0.136, 95%CI=0.022-0.828). No significant difference was found between the two populations in genotype frequencies of all other SNPs.</p><p><b>CONCLUSION</b>The polymorphisms of the MYOC gene may be related to POAG.</p>

Genetic and environmental risk factors for primary open-angle glaucoma / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Primary open-angle glaucoma (POAG) is characterized by optic nerve damage and consists of a group of genetically heterogeneous disorders. This study was to investigate the associations of genetic and environmental factors with POAG in a hospital-based Chinese population.</p><p><b>METHODS</b>Thirty-two adult onset POAG patients and 96 age-sex matched control subjects were studied by multivariable logistic regression analysis for the relationships between POAG and its risk factors including family history, diabetes, hypertension, cardiovascular diseases, cigarette smoking, alcohol consumption and polymorphisms of the myocilin and the optineurin genes.</p><p><b>RESULTS</b>Univariate analysis showed that POAG was related to family history, cardiovascular disease, alcohol consumption and a myocilin sequence alteration (T353I) (P < 0.04). Multivariable logistic regression analysis confirmed that POAG was significantly associated with family history (OR = 20.2), hypertension (OR = 3.58), cigarette smoking (OR = 10.8), alcohol consumption (OR = 0.028) and T353I (OR = 6.03, all P < 0.05).</p><p><b>CONCLUSIONS</b>Family history, hypertension, cigarette smoking and T353I in the myocilin gene are risk factors for POAG. Alcohol consumption, however, has a protective effect.</p>

Mutation-function analysis in the lipoprotein lipase gene of Chinese patients with hypertriglyceridemic type 2 diabetes / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the role of lipoprotein lipase (LPL) gene on Chinese patients with hypertriglyceridemic type 2 diabetes.</p><p><b>METHODS</b>Three subject groups, including hypertriglyceridemic group, normalipidemic type 2 diabetes group and healthy controls, were recruited and screened for sequence changes in LPL gene with PCR, SSCP, restriction analysis and direct DNA sequencing. LPL mass and activity in post-heparin plasma and in in vitro expression were investigated. Comparative modeling was performed via Swiss-PDB Viewer to provide the potential 2-D structures of wildtype and mutant proteins.</p><p><b>RESULTS</b>Four missense mutations, Ala71Thr, Val18Ile, Gly188Glu and Glu242Lys, were identified in patients with hypertriglyceridemic type 2 diabetes, and not in both normalipidemic diabetes and the control subjects. The four missense mutations were located in the highly conserved amino acid sites, which are involved in highly conserved exon 3, 5, or 6 regions. They led to reduced LPL mass and enzyme activities in both post-heparin plasma and in vitro expression. The modeled structures displayed the differences to a great extent between the mutant and wide-type molecules.</p><p><b>CONCLUSION</b>These results indicated that the 4 missense mutations lead to LPL deficiency and subsequent hypertriglyceridemia. The LPL deficiency predispose a progressive diabetic pathway to those affected individuals. LPL gene is one of susceptibility gene for hypertriglyceridemic type 2 diabetes.</p>

Screening for point mutations in rhodopsin gene among one hundred Chinese patients with retinitis pigmentosa / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To test the frequency and pattern of rhodopsin (RHO) mutations in Chinese retinitis pigmentosa (RP) patients and to evaluate their effects in the pathogenesis of RP.</p><p><b>METHODS</b>Genomic DNA was extracted from peripheral blood samples of 100 Hong Kong Chinese RP patients. Sequence variants of the entire coding exons of the RHO gene were tested using PCR, conformation sensitive gel electrophoresis and DNA sequencing.</p><p><b>RESULTS</b>Totally six nucleotide changes were identified, among which three were silent mutations, two missense mutations and one deletion mutation. P347L was found in one RP proband and her three children who also had RP. P327(1 bp del) was novel and detected in a late-onset RP patient of 53 years. Her 26-year-old daughter, also carrying the identified mutation, had no RP phenotypes except for the mottled retinal pigment epithelium (RPE) revealed by fundal examination. Neither of the two mutations was detected in normal controls.</p><p><b>CONCLUSION</b>Two patients had disease-causing mutations in the RHO gene, thus RHO mutations cause about 2.0% (95% confidence interval: 0.2%-7.0%) of all RP among Chinese in Hong Kong. A highly conserved C-terminal sequence QVS(A)PA was altered due to P347L and thereby resulting in an aberrant subcellular localization of rhodopsin. Loss of all six phosphorylatable residues at the C-terminus and the highly conserved C-terminal sequence QVS(A)PA may occur because of P327(1 bp del). To elucidate the predominant biochemical defects in such mutant, transgenic mice and transfected culture cells carrying P327(1 bp del) would be of greatest value.</p>

Screening for mutations in a novel retinal-specific gene among Chinese patients with retinitis pigmentosa / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To identify and evaluate mutations in the RP1 gene among Chinese patients with retinitis pigmentosa (RP).</p><p><b>METHODS</b>Leukocyte DNA of 92 RP patients were collected in Hong Kong. Sequence changes of the entire coding region of the RP1 gene were examined using PCR, conformation sensitive gel electrophoresis and DNA sequencing.</p><p><b>RESULTS</b>In total, 1 nonsense mutation and 1 nonsense variant as well as 10 missense alterations were identified in the RP1 gene, among which, Arg677Ter was found in 1 RP patient and another nonsense variant, Arg1933Ter, was identified in 3 normal individuals and 1 patient with Stargardt's disease, suggesting its nonpathogenicity. Arg77Ter is expected to lead to large disruptions of the encoded protein.</p><p><b>CONCLUSIONS</b>The nonpathogenicity of Arg1933Ter indicates that the C-terminal 224 residues of RP1 protein may be not critical for RP1. The most C-terminal truncation previously reported was due to Tyr1053 (1-bp del) and occurred in RP patients. Thus RP can be caused by reduction in the level of the region of RP1 protein after codon 1052 but before 1933. To ascertain such a proposition, genotypes of more RP patients may reveal more RP causative mutations and more sequence alterations different than those of other ethnic groups.</p>

Mutation analysis of retinitis pigmentosa 1 gene in Chinese with retinitis pigmentosa / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the frequency and pattern of RP1 point mutations in Chinese retinitis pigmentosa (RP) patients and to examine their effects on the development of RP.</p><p><b>METHODS</b>Conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing were used to determine sequence alterations occurring in the entire coding region of the RP1 gene in 101 Chinese RP patients in Hong Kong.</p><p><b>RESULTS</b>R677X was detected in one RP patient. A nonpathogenic nonsense mutation, R1933X, was identified in three normal individuals and one patient with Stargardt disease. The frequency of RP1 mutations among all RP patients in this study is 1/101. R677X is expected to lead to large disruptions of the encoded protein. Additionally, 10 more missense alterations in the RP1 gene were identified in the subjects of this study. Apart from M479I whose pathogenicity can not be determined currently, other sequence changes are just polymorphisms of the RP1 gene.</p><p><b>CONCLUSION</b>The nonpathogenicity of R1933X indicates that the C-terminal 224 residues of RP1 protein may be not critical for RP1. Recently, a C-termnal truncating mutation, Y1053(1 bp del), was reported to occur in an RP patient. Thus RP can be caused by lack of the region of RP1 protein after codon 1052 but before 1933. To confirm such a proposition, a large genotyping study is necessary and is likely to reveal more RP causative mutations and uncover more sequence alterations different from those of other ethnic groups.</p>