Biomedical subjects

Dan Yi Wang

Publications and source records attributed to Dan Yi Wang.

8 recordsLinked to original sources

PubMed2006

A genome-wide scan maps a novel juvenile-onset primary open angle glaucoma locus to chromosome 5q.

PURPOSE: To map the disease-associated locus of a family with autosomal dominant juvenile-onset primary open angle glaucoma (JOAG) and to screen the novel glaucoma gene WD repeat domain 36 (WDR36). METHODS: Complete ophthalmic examination and genomic DNA were obtained from 27 family members, in which nine were confirmed JOAG patients. Myocilin (MYOC), optineurin (OPTN), and WDR36 were screened for mutations by polymerase chain reaction and direct sequencing. Genome-wide scanning was carried out using the ABI PRISM Linkage Mapping Set MD-10. Two-point and multipoint linkage analyses were performed with the MLINK, ILINK, and LINKMAP programs. For fine mapping, additional markers flanking the most promising region on chromosome 5q were also analyzed. The significance of LOD scores was tested with simulation analyses using FASTLINK. Haplotypes were constructed using Simwalk2. RESULTS: MYOC or OPTN mutations were excluded in all family members. A maximum LOD score value of 4.82 at theta=0.00 was obtained for the marker D5S2011. Markers D5S2065, D5S1384, D5S471, D5S503, D5S2098, and D5S638 had LOD score values over 4.0 at theta=0.00. Haplotype analysis and recombination mapping further confined this region to 5q22.1-q32 within a region of 36 Mb flanked by D5S2051 and D5S2090. Screening of the novel WDR36 glaucoma-associated gene, which lies centromeric to the disease interval, revealed no mutations within any of the 23 coding exons or splicing junctions. CONCLUSIONS: Our results provided the mapping of a novel locus for JOAG at 5q and excluded coding or splicing junctions mutations within the WDR36 gene.

Adolescent↗

PubMed2006

Molecular diagnostics of genetic eye diseases.

Eye diseases can be simple or complex, and mostly of heterogeneous molecular genetics. Some eye diseases are caused by mutations in a single gene, but some diseases, such as primary open angle glaucoma, can be due to sequence variations in multiple genes. In some diseases, both genetic and epigenetic mechanisms are involved, as was recently revealed in the mechanism of retinoblastoma. Disease causative mutations and phenotypes may vary by ethnicity and geography. To date, more than a hundred candidate genes for eye diseases are known, although less than 20 have definite disease-causing mutations. The three common genetic eye diseases, primary open angle glaucoma, age-related macular degeneration, and retinitis pigmentosa, all have known gene mutations, but these account for only a portion of the patients. While the search for eye disease genes and mutations still goes on, known mutations have been utilized for diagnosis. Genetic markers for pre-symptomatic and pre-natal diagnosis are available for specific diseases such as primary open angle glaucoma and retinoblastoma. This paper reviews the molecular basis of common genetic eye diseases and the available genetic markers for clinical diagnosis. Difficulties and challenges in molecular investigation of some eye diseases are discussed. Establishment of ethnic-specific disease databases that contain both clinical and genetic information for identification of genetic markers with diagnostic, prognostic, or pharmacological value is strongly advocated.

Eye Diseases, Hereditary↗

PubMed2006

Novel myocilin mutation in a Chinese family with juvenile-onset open-angle glaucoma.

OBJECTIVE: To search for the genetic cause of juvenile-onset open-angle glaucoma (JOAG) in a Chinese family. METHODS: In a 3-generation glaucoma family affected with JOAG or ocular hypertension, we screened myocilin (MYOC) and optineurin (OPTN) for mutations and investigated apolipoprotein E (APOE) polymorphisms in 6 family members, 2 of them patients with JOAG, 2 patients with ocular hypertension, and 2 patients who were asymptomatic. Normal controls included 200 unrelated Chinese subjects. The COS-7 cell line was transfected with expression vectors encoding wild-type or mutated MYOC complementary DNA. Cellular and secreted MYOC proteins were characterized by Western blotting. RESULTS: One missense MYOC mutation, 734G>A: Cys245Tyr, was identified. It occurred in all 4 family members afflicted with JOAG or ocular hypertension but not in asymptomatic family members. No OPTN variations were observed. APOE polymorphism frequencies were similar to those for controls. The Cys245Tyr MYOC mutation cosegregated with the disorder within the family. It was absent in the 200 control subjects. The Cys245Tyr mutant MYOC protein formed homomultimeric complexes that migrated at molecular weights larger than their wild-type counterparts. These mutant complexes remained sequestered intracellularly in COS-7 cells. CONCLUSIONS: The Cys245Tyr MYOC mutation was the genetic cause of JOAG in this Chinese family. This mutation may alter covalent bonds that formed between MYOC cysteines. Clinical Relevance Genetic tests of MYOC mutations may be beneficial to predict new cases of the disease in families with JOAG.

Adolescent↗

PubMed2006

Association of apolipoprotein E polymorphisms with normal tension glaucoma in a Chinese population.

PURPOSE: To evaluate the role of apolipoprotein E (APOE) polymorphisms in primary open angle glaucoma (POAG). METHODS: A cohort of 400 unrelated Chinese POAG patients was examined, including 294 cases of high tension glaucoma (HTG) and 106 with normal tension glaucoma (NTG). Also studied were 300 unrelated Chinese control subjects. The genotypes of the APOE polymorphisms in exon 4 and in the promoter at positions -491, -427, and -219 were determined by polymerase chain reaction and restriction endonuclease analysis. Frequencies of the genotypes were compared between patients and controls by chi test or Fisher exact test. The association of APOE polymorphisms with POAG phenotypes including age at diagnosis, intraocular pressure (IOP) at diagnosis, highest IOP, cup-disc ratio, and visual field score was investigated by the Kruskal-Wallis test. RESULTS: No significant difference was detected in the frequencies of APOE promoter polymorphisms between POAG patients and control subjects (P>0.0125). For the exon 4 polymorphism, when compared with control subjects, the frequency of epsilon 4 carriers was significantly lower in patients with NTG (P=0.008; odds ratio=0.36, 95% confidence interval=0.17, 0.79) but not in HTG (P=0.07). Compared with -219TT, the -219G carriers had a significant higher age at diagnosis (P=0.0046). No significant association was found between other APOE polymorphisms and POAG phenotypes (P>0.07). CONCLUSIONS: Our findings suggest that the APOE epsilon 4 allele confers a protective effect against NTG, whereas the APOE promoter polymorphisms do not contribute to POAG risk. However, the APOE -219G carriers tended to have later-onset POAG.

Adolescent↗

PubMed2006

A genome-wide scan maps a novel juvenile-onset primary open-angle glaucoma locus to 15q.

PURPOSE: To map the disease-associated locus of a family with autosomal dominant juvenile-onset primary open-angle glaucoma (JOAG). METHODS: A complete ophthalmic examination was conducted, and genomic DNA was obtained from 25 members of a Chinese family, of which eight were confirmed as having JOAG. Myocilin (MYOC), optineurin (OPTN), and WD repeat-domain 36 (WDR36) were screened for sequence alterations, by PCR and direct sequencing. Subsequently, a genome-wide scan was performed (Prism Linkage Mapping Set MD-10; Applied Biosystems, Inc., Foster City, CA). Two-point and multipoint linkage analyses were performed with the MLINK, ILINK, and LINKMAP programs. For fine mapping, additional markers flanking the most promising region on 15q were analyzed. The significance of the lod score was tested with simulation analyses by using FASTLINK. Haplotypes were constructed with Simwalk2. Three candidate genes, NR2E3, SMAD6, and CLN6, located within the critical region, were screened for mutations. RESULTS: MYOC, OPTN, and WDR36 mutations were excluded in all family members. A maximum two-point lod score of 3.31 at theta = 0.0 was obtained for the marker D15S125. Four adjacent markers, rs2030040, rs169169963, D15S153, and D15S131, gave two-point lod scores of 2.41, 2.90, 3.02, and 2.68, respectively, at theta = 0.0. Haplotype analysis and recombination mapping further confined this region to 15q22-q24 within a genetic distance of 16.6 Mb flanked by D15S1036 and rs922693. No mutations were found in the coding exons and splicing junctions of NR2E3, SMAD6, and CLN6. CONCLUSIONS: The results provide evidence for the mapping of a novel locus for JOAG at 15q22-q24. A further search for the disease-causing gene in this new JOAG locus is in progress.

Adolescent↗

PubMed2005

Gene mapping for primary open angle glaucoma.

Primary open angle glaucoma (POAG) is a leading cause of visual impairment and blindness worldwide. To date, at least 20 genetic loci for POAG have been reported. Only 3 causative genes are identified from these loci: myocilin (MYOC), optineurin (OPTN) and WD repeat domain 36 (WDR36), which together account for less than 10% of POAG. Only a portion of POAG follows Mendelian inheritance, and a considerable fraction results from a large number of variants in several genes, each contributing small effects. Over the past 10 years, there has been vigorous research on mapping the POAG genes. The main technological approaches are functional cloning, family linkage analysis, genome-wide scan, case-control association study, and microarray analysis. Association studies found 16 genes related to POAG, but reports on glaucoma-causing effects of these genes are conflicting. Ten microarray gene expression studies related to POAG have been published. A number of genes potentially related to POAG have been identified, and they provide a good resource to select candidate genes for mutation analysis in association studies. While linkage studies remain a mainstay, the current trend is to use genome-wide association studies to map genes for POAG. This review gives an overview of the efforts in the past decade to identify the POAG genes through linkage studies, genome-wide scans, case-control association studies and microarray studies. In the near future such comprehensive studies are expected to greatly advance our understanding of the genetic basis of POAG and provide information for effective glaucoma therapy.

Chromosome Mapping↗

PubMed2005

SNPs and interaction analyses of myocilin, optineurin, and apolipoprotein E in primary open angle glaucoma patients.

PURPOSE: To evaluate the association of myocilin (MYOC), optineurin (OPTN), and apolipoprotein E (APOE) genes and their interactions in primary open angle glaucoma (POAG). METHODS: A cohort of 400 unrelated POAG patients (294 high tension glaucoma, HTG, and 106 normal tension glaucoma, NTG) and 281 unrelated control subjects were recruited. All coding exons and splicing junctions in MYOC and OPTN were screened for sequence alterations. Common polymorphisms in APOE were genotyped. Single genes were investigated by univariate and haplotype analysis, and gene-gene interactions by logistic regression and stratified analysis. Multiple comparisons were corrected by the Bonferroni method. Bioinformatics analysis was performed to assess the conservation of mutation sites across species and to predict putative motifs and secondary structures in mutated proteins. RESULTS: Disease-causing mutations in MYOC and OPTN were identified in 1.75% and 1% of POAG patients, respectively. Most of these mutations were highly conserved across species, many predicted to create new motifs or change protein secondary structures. No individual MYOC polymorphisms significantly contributed to HTG or NTG. A haplotype containing the minor allele of the MYOC IVS2+35A>G increased NTG risk (p=0.0001). Three OPTN polymorphisms, T34T, IVS5+38T>G, and IVS8-53T>C increased NTG risk (p<0.0008), while IVS5+38T>G increased HTG risk (p=0.0006). One haplotype that contains the minor alleles of 3 OPTN polymorphisms, T34T, IVS5+38T>G, and IVS7+24G>A, increased NTG risk (p=0.0002). APOE epsilon4 carriers had a decreased NTG risk (p=0.007). Possible gene-gene interactions were found between MYOC, OPTN, and APOE. CONCLUSIONS: Disease-causing mutations in MYOC and OPTN accounted for only a small proportion of Chinese POAG patients. Common polymorphisms in MYOC, OPTN, and APOE might interactively contribute to POAG, indicating a polygenic etiology.

Adolescent↗

PubMed2004

Absence of myocilin and optineurin mutations in a large Philippine family with juvenile onset primary open angle glaucoma.

PURPOSE: To analyze the role of the two primary open angle glaucoma (POAG) genes, myocilin (MYOC) and optineurin (OPTN), in a large Philippine family segregating autosomal dominant juvenile onset open angle glaucoma (JOAG). METHODS: The coding sequences of the MYOC and OPTN genes were screened in 27 family members by polymerase chain reaction and direct sequencing. The specific MYOC promoter polymorphism (MYOC.mtl) was identified by restriction endonuclease assay. All of the ABI MD-10 microsatellite markers on chromosomes 1, 2, 3, 7, 8, and 10, which harbor the six known POAG loci, were analyzed for linkage with POAG. RESULTS: No mutation was identified in this large kindred. Instead, three polymorphisms (-80G->A, -1000G->C, R76K) in MYOC and four polymorphisms (T34T, M98K, R545Q, IVS7+24G->A) in OPTN were found. All markers flanking the six known POAG loci gave LOD scores not more than 1.1. Non-parametric linkage analysis for all these markers resulted in p values more than 0.05. CONCLUSIONS: Both mutation testing and linkage analysis provide strong evidence against MYOC and OPTN being the causative gene in this large family. It indicates that unidentified genes will underlie the occurrence of glaucoma in this family.

Adult↗