[Frontiers in Bioscience 16, 2052-2059, June 1, 2011]
Confirmation and further mapping of the GLC3C locus in primary congenital glaucoma
Xueli Chen1,2 Yuhong Chen1,2, Li Wang1,2, Deke Jiang3, Wenzhang Wang3, Mingying Xia4, Long Yu3,4, Xinghuai Sun1,2
1
TABLE OF CONTENTS
1. ABSTRACT
We investigated the relationship between primary congenital glaucoma (PCG) in the Chinese Han population and its candidate locus GLC3C. 152 nuclear families (patients with normal parents) without carrying the CYP1B1 mutation were enrolled. Fluorescence Labeled Multiplex-PCR was used to genotype 12 short tandem repeats (STRs) within GLC3C region and transmission disequilibrium test (TDT) was used to analyze the association between PCG and these STR markers. Sixteen haplotype tag single nucleotide polymorphisms (htSNPs) were chosen from the location where the TDT tests showed positive results. Matrix-assisted laser desorption/ionization Time-of-flight (MALDI-TOF) mass spectrometry was used to perform SNP genotyping Haplotypes constructed from these SNPs were analyzed. The TDT results of STRs in the GLC3C area indicated that D14S279, D14S555 and D14S74 have significant transmission disequilibrium signals (p = 0.0210, 0.0096 and 0.0034), with a genetic distance of 0.006cM among them. Significant transmission disequilibrium (P=0.0010) occurred between the haplotype TAACG of rs2111701- rs4020123- rs4903696- rs11159318- rs177216 and the disease. Detection of disease causing genes within this region needs further study.
2. INTRODUCTION
Glaucoma is the second leading cause of vision loss in the world. About 67 million people suffer from glaucoma around the world and it is estimated that 5.2 million to 6.7 million of them have lost their eyesight (1). Of particular interest, Primary Congenital Glaucoma (PCG) severely limits an infant's visual development, which could result in life-long visual disability and may be classified as a major birth defect (2). The attack rate of PCG in newborns has distinct racial and regional differences. The incidence of PCG in newborns in western countries is 1:10000 (1:5000～1:22000) on average, with maximum occurrence in gypsies of Slovakia, which has been reported as 1:1250, and it is 1:10000 in Chinese Han newborns.
Among all the PCG cases, only 10-12% have family histories of this disease and most of the remainder cases are sporadic. It is reported that sporadic cases are closely related to heredity as well (3), and there is heterogeneity among different cases. Most of the inherited forms of glaucoma are presented as autosomal recessive with penetrance of 40-100% (3-5). Minority families exhibit autosomal pseudooverdominance inheritance, while the current viewpoint tends to imply it is polygenetic or multifactorial inheritance (6).
At present, according to family-based linkage analysis, three major loci were identified to be related to the onset of PCG, GLC3A (2p21) (7), GLC3B (1p36.2-p36.1) (8) and GLC3C (l4q24.3) (9). The mutation rate of gene CYP1B1 (11-13) located at the GLC3A site differs dramatically between different patient groups (10), which is 90-100% in Arabs and Gypsies (11), 30-50% in Indonesia and Morocco (12-15), and 20% in Japan (16). The previous research including 116 sporadic cases in the Chinese Han population by this research group shows that only 17.2% patients are caused by the GLC3A mutation (17), which indicates that there must be other disease causing genes present in PCG patients in Chinese Han population. Locus GLC3B was identified from linkage analysis on four families with no relationship to CYP1B1 genes in 1996, localized in lp36.2-p36.1, inside a region of about 3cM (18). There are 16 genes specifically expressed by trabecular meshwork in this area. The third candidate area, GLC3C, was identified by a sperate PCG family of multi-generational autosomal recessive inheritance, localized in 14q24.3, with a genetic distance of about 2.9cM (10). Recently, a study was conducted on two large PCG families of consanguineous marriage in Pakistan identified the causal gene LTBP2 in this region (21, 22). LTBP2 is a potential transforming growth factor binding protein, upstream of GLC3C (22).
Currently, the main methods for causal gene location include family-based linkage analysis and population-based association study. These two methods have their own advantages; however they also have certain limitations. Population association study depends on the linkage disequilibrium between the genetic marker and the disease causing gene, and is subject to the influence of population stratification, which can result in false positive or false negative results. Linkage analysis can be used to seek out relatively large areas and is not subject to the influence of population stratification, however its location precision is dependent on the size of the family and its structure.
Due to most forms of PCG present as autosomal recessive inheritance and the elimination of consanguineous marriage in China, fewer large families with PCG in the Chinese Han population are available for genetic research. In this situation, nuclear families were chosen as the subjects of this study. According to CYP1B1 gene mutation screening, 152 nuclear families that did not carry any CYP1B1 gene mutations were chosen for analysis. After excluding the CYP1B1 gene mutation, the study was focused on observing the relationship between the GLC3C region and PCG. A Transmission Disequilibrium Test (TDT) (23-24) was used to verify the linkage relationship between PCG and this genomic area. Both theoretical and practical examples have proven that TDT has a stronger efficacy in locating complex trait-related candidate gene sites (25-26). In addition, TDT has the advantage of less influenced by sampling bias, such as population stratification, sample stratification, etc.
3. MATERIALS AND METHODS
3.1. Sample diagnosis and collection
3.1.1. Clinical examination
Slit lamps and surgical microscopes were used to observe the anterior segment, gonioscopes were used to observe the structure of chamber angle, and adirect ophthalmoscopes were used to observe the ocular fundus. Tono-PEN® was used to measure the intraocular pressure prior to or during surgery.
3.1.2.Case diagnosis
Diagnostic standard of PCG: Onset age is less than three years; cornea has accretion or edema, intraocular pressure is greater than 21mmHg and cup disk ratio is enlarged or dissymmetrical between two eyes. Diseases such as congenital macrocornea, apriority, Fuch's dystrophy, ocular trauma/birth trauma, intro-ocular placeholder, and other congenital anomalies of secondary glaucoma, such as Aniridia, Neuroinomatosis, Sturge-Weber Symptom Complex, Axenfeld-Rieger Complex, Peter's Anomaly, Iridocorneal Endothelial Syndrome (ICE), etc, were excluded.
3.1.3. Sample collection
1-3mL of peripheral blood was obtained from each patient with PCG and their parents using an ACD anticoagulative tube. Samples were stored in a -20° C freezer. All research subjects were from Chinese Han population. All the PCG patients were pre-screened CYP1B1 gene mutation in a former study (the results are reported separately). 152 nuclear families (patients and their parents) were enrolled. There was no consanguineous marriage in any of the families in our study. Parents of the patients were free of any hereditary eye-disease. All of the research subjects agreed to participate the study and signed consent forms regarding the donation of a sample for scientific research, as approved by the Ethics Committee of the Eye and ENT hospital, Fudan University.
3.2. Genotyping
3.2.1. Short tandem repeat (STR) genotyping
15 STRs were selected from the GLC3C region (Table 1). Fluorescence Labeled Multiplex-PCR was used to perform STR amplification. The amplified products were loaded and results were recorded on an ABI 3730xl DNA analyzer (Applied Biosystems, Foster, CA, USA).
3.2.2. Single nucleotide polymorphism (SNP) genotyping
Based on the results of STRs analysis, 17 haplotype tag SNPs (htSNPs) were identified within 40kb upstream and 40kb downstream of the positive STRs area. These markers were subjected to further accurate the region of transmission disequilibrium (Table 2). Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was used to complete the genotyping for htSNPs by using a time-of-flight mass-based biochip system (MassARRAY™) platform (27-29). As a result of the analysis, 16 htSNPs were successfully genotyped.
3.3. Data analysis
3.3.1.Transmission disequilibrium test (TDT)
TDT is a type of linkage analysis which can detect linkage in regions with linkage disequilibrium and also detect if linkage exists by comparing the ratio of transmission and non-transmission of an allele (23-24). A non-transmission allele was used as an internal control for the transmission allele and can theoretically eliminate the influence of sample stratification. According to the mathematical model, null hypothesis (H0) assumes the probability for heterozygous parents to transmit any allele to an infant is equivalent, i.e. 50%, when the restructuring of a genetic marker and the disease site is completely random; therefore there is no linked relationship among them. Conversely, if a genetic marker and the disease site are closely linked, (H1) the specific allele has more likelihood to be transmitted by the heterozygous parents to their affected offspring.
12 out of the 15 STRs within the GLC3C area were typed successfully in 152 nuclear families. GeneMapper3.7 software (Applied Biosystems) was used to analyze the STR genotyping results. TDT was used to analyze the transmission condition of the alleles of each STR. 17 htSNPs were selected in the positive area, indicated by the results of STR analysis. This same method was used to test the transmission disequilibrium of the 16 successfully typed SNPs in the nuclear families. Unphased 3.0.13 software was used to analyse the TDT for STRs (30-31), and Haploview 4.1 software was used to analyse the TDT for SNPs.
3.3.2. Haplotype analysis
In order to observe if there is an advantageous haplotype in the diseased samples, we analyzed haplotypes constructed from 16 SNPs which had been typed successfully. The Haploview 4.1 software package was used to analyze linkage disequilibrium block and association. A chi-square test was used to evaluate the linkage intensity between each haplotype and patient, and a permutation test was used to correct multiple tests.
4. RESULTS
The TDT tests for single STR showed that D14S279, D14S555 and D14S74 had statistical significance (p values = 0.0221, 0.0096, and 0.0034, respectively) (Table 3). The genetic distance of these three STRs is about 0.006cM, which indicates a strong linkage region for transmission in the patients with PCG.
In our data, the heterozygosity of a single SNP is quite low. As a result, none of the SNPs showed statistical significant assocations. Then haplotypes were constructed based on the genotyping data of 16 SNPs, and the transmission disequilibrium of each haplotype block was analyzed inside each nuclear family. (Figure 2 and Table 5) These results showed that the TAACG haplotype of rs2111701- rs4020123- rs4903696- rs11159318- rs177216 was significantly (p ＝ 0.0010) associated with the disease. After 10000 iterations of the Permutation test, this haplotype remained significant (p ＝ 0.0135) (Table 6)
5. DISCUSSION
At present, STR or SNP markers have mainly been used in applying the principle of linkage disequilibrium to locate a disease-related gene. To improve the effectiveness of analysis of linkage disequilibrium in researching nuclear families of PCG, we combined the usage of these two different types of genetic markers, STR and SNP. On the basis of results of transmission disequilibrium by using STRs, we further supplemented our research by using tag SNPs to conduct verification, perform a more elaborate analysis, and ascertain the signals linked with the phenotype of glaucoma in a smaller region.
To reduce the required number of SNPs for genotyping, tag SNPs within the candidate region were selected. The efficiency of genotyping data can be dramatically improved by using the enormous amount of SNP data generated from the international HapMap project, combined with linkage disequilibrium blocks. When the linkage disequilibrium area is large, the information within the region can usually be delegated by a small number of SNPs. The markers necessary in obtaining a majority or all of the information of linkage disequilibrium are called htSNP (37). By typing a small number of tag SNPs, all or most of the information regarding linkage disequilibrium in the region, including the frequency of common haplotypes, can be obtained. Thus, there is no need to analyze all of the common variances within the region or the entire genome. Using htSNP, the region and phenotype association studies can be conducted effectively (38). There are a variety of statistical methods (36, 38) used for the definition of htSNP. In this study, haplotype blocks were determined and haplotypes were constructed based on the HapMap Phase I data of Chinese Han Population by using Gabriel's method (confidence intervals) (39). In practice, it was found that haplotype blocks and htSNP are not identical under different methods. Therefore, in order to obtain more accurate positioning results, functional validation, larger sample size studies and multiple repetitions within different populations, as well as cellular and animal models, are necessary.
Analysis of the results of STRs, especially htSNPs data, indicates that the area of haplotype TAACG inside GLLC3C or nearby regions carries a pathogenic mutation related to PCG. This region contains a 22kb interval of high-risk haplotype (as defined by htSNPs) and has no known genes but only one pseudogene, FRDAP. FRDAP has a coding sequence by functional prediction; there is no evidence of transcription or function-related information so far. However, it is possible that markers in this region are in linkage disequilibrium with the deleterious mutation on the causable gene, which is not necessarily nearby. Further studies will be needed to evaluate the association of this region and discover the real PCG causing gene.
6. ACKNOWLEDGMENTS
This paper was supported by grants from the National Natural Science Foundation of China (81000401, 81020108017, 30973264), and the National Basic Research Program of China (2007CB512204).
7. REFERENCES
1. Quigley HA. Number of people with glaucoma worldwide. Br J Ophthalmol, 80(5): 389-93. (1996)
doi:10.1136/bjo.80.5.389
PMid:8695555 PMCid:505485
2. Arnold C, Christopher PH and Bernadette M. Global report on birth defects: The hidden toll of dying and disabled children. New York: March of Dimes Birth defects Foundation. (2006)
3. Li Meiyu. Glaucoma. Beijing: People's medical publishing house, 515-9. (2004)
4. Li Fengming. YANKEQUANSHU. Beijing:People's medical publishing house, 1962-74. (1996)
5. Hu DN. Prevalence and mode of inheritance of major genetic eye diseases in China. J Med Genet, 24(10):584-8. (1987)
doi:10.1136/jmg.24.10.584
PMid:3500313 PMCid:1050283
6. Gencik A, Gencikova A and Ferak V. Population genetical aspects of primary congenital glaucoma. I. Incidence, prevalence, gene frequency, and age of onset. Hum Genet, 61(3):193-7. (1982)
doi:10.1007/BF00296440
7. Sarfarazi M, Akarsu AN and Hossain A. Assignment of a locus (GLC3A) for primary congenital glaucoma (buphthalmos) to 2p21 and evidence for genetic heterogeneity (J). Genomics, 30(2):171-7. (1995)
doi:10.1006/geno.1995.9888
PMid:8586416
8. Akarsu AN, Turacli ME, Aktan SG, Barsoum-Homsy M, Chevrette L, Sayli BS and Sarfarazi M. A second locus (GLC3B) for primary congenital glaucoma (Buphthalmos) maps to the 1p36 region. Hum Mol Genet, 5(8):1199-203. (1996)
doi:10.1093/hmg/5.8.1199
PMid:8842741
9. Stoilov IR and Sarfarazi M. The third genetic locus (GLC3C) for primary congenital glaucoma (PCG) maps to chromosome l4q24.3. The Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting, Fort Lauderdale (FL). (2002).
10. Chakrabarti S, Kaur K, Kaur I, Mandal AK, Parikh RS, Thomas R and Majumder PP. Globally, CYP1B1 mutations in primary congenital glaucoma are strongly structured by geographic and haplotype backgrounds. Invest Ophthalmol Vis Sci, 47(1):43-7. (2006)
doi:10.1167/iovs.05-0912
11. Bejjani BA, Stockton DW, Lewis RA, Tomey KF, Dueker DK, Jabak M, Astle WF and Lupski JR. Multiple CYP1B1 mutations and incomplete penetrance in an inbred population segregating primary congenital glaucoma suggest frequent de novo events and a dominant modifier locus. Hum Mol Genet, 9(3):367-74. (2000)
doi:10.1093/hmg/9.3.367
PMid:10655546
12. Sitorus R, Ardjo SM, Lorenz B and Preising M. CYP1B1 gene analysis in primary congenital glaucoma in Indonesian and European patients. J Med Genet, 40(1):e9. (2003)
doi:10.1136/jmg.40.1.e9
PMCid:1735251
13. Belmouden A, Melki R and Hamdani M. A novel frameshift founder mutation in the cytochrome P450 1B1 (CYP1B1) gene is associated with primary congenital glaucoma in Morocco. Clin Genet, 62(4):334-9. (2002)
doi:10.1034/j.1399-0004.2002.620415.x
PMid:12372064
14. Reddy AB, Kaur K, Mandal AK, Panicker SG, Thomas R, Hasnain SE, Balasubramanian D, Chakrabarti S. Mutation spectrum of the CYP1B1 gene in Indian primary congenital glaucoma patients. Mol Vis, 10: 696-702. (2004)
PMid:15475877
15. Panicker SG, Mandal AK, Reddy AB, Gothwal VK and Hasnain SE. Correlations of genotype with phenotype in Indian patients with primary congenital glaucoma. Invest Ophthalmol Vis Sci, 45(4):1149-56. (2004)
doi:10.1167/iovs.03-0404
16. Mashima Y, Suzuki Y, Sergeev Y, Ohtake Y, Tanino T, Kimura I, Miyata H, Aihara M, Tanihara H, Inatani M, Azuma N, Iwata T and Araie M. Novel cytochrome P4501B1 (CYP1B1) gene mutations in Japanese patients with primary congenital glaucoma. Invest Ophthalmol Vis Sci, 42(10): 2211-6. (2001)
PMid:11527932
17. Chen Y, Jiang D, Yu L, Katz B, Zhang K, Wan B and Sun X. CYP1B1 and MYOC mutations in 116 Chinese patients with primary congenital glaucoma. Arch Ophthalmol, 126(10): 1443-7. (2008)
doi:10.1001/archopht.126.10.1443
PMid:18852424
18. AN Akarsu, ME Turacli, SG Aktan, M Barsoum-Homsy, L Chevrette, BS Sayli and M Sarfarazi. A second locus (GLC3B) for primary congenital glaucoma (Buphthalmos) maps to the 1p36 region (J). Hum Mol Genet, 1996, 5(8):1199-203.
doi:10.1093/hmg/5.8.1199
PMid:8842741
19. Tomarev SI, Wistow G, Raymond V, Dubois S and Malyukova I. Gene Expression Profile of the Human Trabecular Meshwork: NEIBank Sequence Tag Analysis. Invest Ophthalmol Vis Sci, 44(6): 2588-96. (2003)
doi:10.1167/iovs.02-1099
20. Kuchtey J, Kallberg ME, Gelatt KN, Rinkoski T, Komaromy AM and Kuchtey RW. Angiopoietin-like 7 Secretion Is Induced by Glaucoma Stimuli and Its Concentration Is Elevated in Glaucomatous Aqueous Humor. Invest Ophthalmol Vis Sci, 49(8): 3438-48. (2008)
doi:10.1167/iovs.07-1347
21. Sabika Firasat, S. Amer Riazuddin, J. Fielding Hejtmancik and Sheikh Riazuddin. Primary congenital glaucoma localizes to chromosome 14q24.2-24.3 in two consanguineous Pakistani families. Mol Vis, 14:1659-65. (2008)
PMid:18776954 PMCid:2530517
22. Narooie-Nejad M, Paylakhi SH, Shojaee S, Fazlali Z, Rezaei Kanavi M, Nilforushan N, Yazdani S, Babrzadeh F, Suri F, Ronaghi M, Elahi E and Paisán-Ruiz C. Loss of Function Mutations in the Gene Encoding Latent Transforming Growth Factor Beta Binding Protein 2, LTBP2, Cause Primary Congenital Glaucoma. Human Molecular Genetics, 18(20), 3969-77. (2009)
doi:10.1093/hmg/ddp338
PMid:19656777
23. Zhao H. Family-based association studies. Stat Methods Med Res, 9(6): 563-87. (2000)
doi:10.1191/096228000668447080
PMid:11308071
24. Hinds DA, Stokowski RP, Patil N, Konvicka K, Kershenobich D, Cox DR and Ballinger DG. Matching strategies for genetic association studies in structured populations. Am J Hum Genet, 74(2): 317-25. (2004)
doi:10.1086/381716
PMid:14740319
25. Spielman RS, McGinnis RE and Ewens WJ. Transmission test for linkage disequilibrium: the insulin gene region and insulin-dependent diabetes mellitus (IDDM). Am J Hum Genet, 52(3): 506-13. (1993)
PMid:8447318 PMCid:1682161
26. Abecasis GR, Cookson WO and Cardon LR. Pedigree tests of transmission disequilibrium. Eur J Hum Genet, 8(7): 545-51. (2000)
doi:10.1038/sj.ejhg.5200494
PMid:10909856
27. Zhang XJ, Huang W, Yang S, Sun LD, Zhang FY, Zhu QX, Zhang FR, Zhang C, Du WH, Pu XM, Li H, Xiao FL, Wang ZX, Cui Y, Hao F, Zheng J, Yang XQ, Cheng H, He CD, Liu XM, Xu LM, Zheng HF, Zhang SM, Zhang JZ, Wang HY, Cheng YL, Ji BH, Fang QY, Li YZ, Zhou FS, Han JW, Quan C, Chen B, Liu JL, Lin D, Fan L, Zhang AP, Liu SX, Yang CJ, Wang PG, Zhou WM, Lin GS, Wu WD, Fan X, Gao M, Yang BQ, Lu WS, Zhang Z, Zhu KJ, Shen SK, Li M, Zhang XY, Cao TT, Ren W, Zhang X, He J, Tang XF, Lu S, Yang JQ, Zhang L, Wang DN, Yuan F, Yin XY, Huang HJ, Wang HF, Lin XY and Liu JJ. Psoriasis genome-wide association study identifies susceptibility variants within LCE gene cluster at 1q21. Nat Genet, 41(2):205-10. (2009)
doi:10.1038/ng.310
PMid:19169255
28. Jurinke C, van den Boom D, Cantor CR and Köster H. The use of MassARRAY technology for high throughput genotyping. Adv Biochem Eng Biotechnol, 77: 57-74. (2002)
doi:10.1007/3-540-45713-5_4
29. Rodi CP, Darnhofer-Patel B, Stanssens P, Zabeau M and van den Boom D. A strategy for the rapid discovery of disease markers using the MassARRAY system. Biotechniques, Suppl: 62-6, 68-9. (2002)
PMid:12083400
30. Dudbridge F. Pedigree disequilibrium tests for multilocus haplotypes. Genet Epidemiol, 25(2):115-21. (2003)
doi:10.1002/gepi.10252
PMid:12916020
31. Dudbridge F. Likelihood-based association analysis for nuclear families and unrelated subjects with missing genotype data. Hum Hered, 66(2):87-98. (2008)
doi:10.1159/000119108
PMid:18382088 PMCid:2386559
32. Gibbs, RA, Belmont, JW, Hardenbol, P, Willis, TD, Yu, FL, Yang, HM, Ch'ang, LY, Huang, W, Liu, B, Shen, Y, Tam, PKH, Tsui, LC, Waye, MMY, Wong, JTF, Zeng, CQ, Zhang, QR, Chee, MS, Galver, LM, Kruglyak, S, Murray, SS, Oliphant, AR, Montpetit, A, Hudson, TJ, Chagnon, F, Ferretti, V, Leboeuf, M, Phillips, MS, Verner, A, Kwok, PY, Duan, SH, Lind, DL, Miller, RD, Rice, JP, Saccone, NL, Taillon-Miller, P, Xiao, M, Nakamura, Y, Sekine, A, Sorimachi, K, Tanaka, T; Tanaka, Y, Tsunoda, T, Yoshino, E, Bentley, DR, Deloukas, P, Hunt, S, Powell, D, Altshuler, D, Gabriel, SB, Qiu, RZ, Ken, A, Dunston, GM, Kato, K, Niikawa, N, Knoppers, BM, Foster, MW, Clayton, EW, Wang, VO, Watkin, J, Gibbs, RA, Belmont, JW, Sodergren, E, Weinstock, GM, Wilson, RK, Fulton, LL, Rogers, J, Birren, BW, Han, H, Wang, HG, Godbout, M, Wallenburg, JC, L'Archeveque, P, Bellemare, G, Todani, K, Fujita, T, Tanaka, S, Holden, AL, Lai, EH, Collins, FS, Brooks, LD, McEwen, JE, Guyer, MS, Jordan, E, Peterson, JL, Spiegel, J, Sung, LM, Zacharia, LF, Kennedy, K, Dunn, MG, Seabrook, R, Shillito, M, Skene, B, Stewart, JG, Valle, DL, Clayton, EW, Jorde, LB, Belmont, JW, Chakravarti, A, Cho, MK, Duster, T, Foster, MW, Jasperse, M, Knoppers, BM, Kwok, PY, Licinio, J, Long, JC, Marshall, PA, Ossorio, PN, Wang, VO, Rotimi, CN, Royal, CDM, Spallone, P, Terry, SF, Lander, ES, Lai, EH, Nickerson, DA, Abecasis, GR, Altshuler, D, Bentley, DR, Boehnke, M, Cardon, LR, Daly, MJ, Deloukas, P, Douglas, JA, Gabriel, SB, Hudson, RR, Hudson, TJ, Kruglyak, L, Kwok, PY, Nakamura, Y, Nussbaum, RL, Royal, CDM, Schaffner, SF, Sherry, ST; Stein, LD and Tanaka, T. The International HapMap Project (J). Nature, 2003, 426(6968): 789-96.
doi:10.1038/nature02168
PMid:14685227
33. Kruglyak L and Nickerson DA. Variation is the spice of life. Nat Genet, (3): 234-6. (2001)
doi:10.1038/85776
PMid:11242096
34. Collins FS, Guyer MS, and Charkravarti A. Variations on a theme: cataloging human DNA sequence variation. Science, 278 (5343): 1580-1. (1997)
doi:10.1126/science.278.5343.1580
PMid:9411782
35. Mary K. Kuhnera, Peter Beerlia, Jon Yamatoa, and Joseph Felsenstein. Usefulness of single nucleotide polymorphism data for estimating population parameters. Genetics, 156 (1): 439-47. (2000)
36. Collins A, Lonjou C, and Morton NE. Genetic epidemiology of single-nucleotide polymorphisms. Proc Nati Acad Sci USA, 96(26): 15173-7. (1999)
doi:10.1073/pnas.96.26.15173
37. Goldstein DB, Ahmadi KR, Weale ME and Wood NW. Genome scans and candidate gene approaches in the study of common diseases and variable drug responses. Trends Genet, 19(11): 615-22. (2003)
doi:10.1016/j.tig.2003.09.006
PMid:14585613
38. Johnson GC, Esposito L, Barratt BJ, Smith AN, Heward J, Di Genova G, Ueda H, Cordell HJ, Eaves IA, Dudbridge F, Twells RC, Payne F, Hughes W, Nutland S, Stevens H, Carr P, Tuomilehto-Wolf E, Tuomilehto J, Gough SC, Clayton DG and Todd JA. Haplotype tagging for the identification of common disease genes. Nat Genet, 29(2): 233-7. (2001)
doi:10.1038/ng1001-233
PMid:11586306
39. Gabriel SB, Schaffner SF, Nguyen H, Moore JM, Roy J, Blumenstiel B, Higgins J, DeFelice M, Lochner A, Faggart M, Liu-Cordero SN, Rotimi C, Adeyemo A, Cooper R, Ward R, Lander ES, Daly MJ and Altshuler D. The structure of haplotype blocks in the human genome. Science, 296(5576): 2225-9. (2002)
doi:10.1126/science.1069424
PMid:12029063
40. Ota M., Katsuyama Y., Tamiya G., Shiina T., Oka A., Ando H. Kimura M., Goto K., Ohno S., Inoko H. and Mizuki N. The Critical Region for Behcet Disease in the Human Major Histocompatibility Complex Is Reduced to a 46-kb Segment Centromeric of HLA-B, by Association Analysis Using Refined Microsatellite Mapping. Am J Hum Genet, 64(5):1406-10. (1999)
doi:10.1086/302364
PMid:10205273
41. Zhang Y, Leaves NI, Anderson GG, Ponting CP, Broxholme J, Holt R, Edser P, Bhattacharyya S, Dunham A, Adcock IM, Pulleyn L, Barnes PJ, Harper JI, Abecasis G, Cardon L, White M, Burton J, Matthews L, Mott R, Ross M, Cox R, Moffatt MF and Cookson WO. Positional cloning of a quantitative trait locus on chromosome 13q14 that influences immunoglobulin E levels and asthma. Nat Genet, 34(2):181-6. (2003)
doi:10.1038/ng1166
PMid:12754510
42. Mizuki N, Ota M, Yabuki K, Katsuyama Y, Ando H, Palimeris GD, Kaklamani E, Accorinti M, Pivetti-Pezzi P, Ohno S and Inoko H. Localization of the Pathogenic Gene of Behc�et's Disease by Microsatellite Analysis of Three Different Populations. Invest Ophthalmol Vis Sci, 41(12): 3702-8. (2000)
PMid:11053265
43. Keicho N, Ohashi J, Tamiya G, Nakata K, Taguchi Y, Azuma A, Ohishi N, Emi M, Park MH, Inoko H, Tokunaga K and Kudoh S. Fine Localization of a Major Disease-Susceptibility Locus for Diffuse Panbronchiolitis. Am J Hum Genet, 66(2):501-7. (2000)
doi:10.1086/302786
PMid:10677310
44. Ota M, Katsuyama Y, Kimura A, Tsuchiya K, Kondo M, Naruse T, Mizuki N, Itoh K, Sasazuki T and Inoko H. A Second Susceptibility Gene for Developing Rheumatoid Arthritis in the Human MHC is Localized within a 70-kb Interval Telomeric of the TNF Genes in the HLA Class III Region. Genomics, 71(3): 263-70. (2001)
doi:10.1006/geno.2000.6371
PMid:11170743
45. Dawson E, Abecasis GR, Bumpstead S, Chen Y, Hunt S, Beare DM, Pabial J, Dibling T, Tinsley E, Kirby S, Carter D, Papaspyridonos M, Livingstone S, Ganske R, Lõhmussaar E, Zernant J, Tõnisson N, Remm M, Mägi R, Puurand T, Vilo J, Kurg A, Rice K, Deloukas P, Mott R, Metspalu A, Bentley DR, Cardon LR and Dunham I. A first-generation linkage disequilibrium map of human chromosome 22. Nature, 418(6897): 544-8. (2002)
doi:10.1038/nature00864
PMid:12110843
46. Bousquet I, Dujardin G and Slonimski PP. ABC1, a novel yeast nuclear gene has a dual function in mitochondria: it suppresses a cytochrome b mRNA translation defect and is essential for the electron transfer in the bc 1 complex (J). EMBO J, 10(8): 2023-31. (1991)
PMid:1648478 PMCid:452883
47. Macinga DR, Cook GM, Poole RK and Rather,PN. Identification and characterization of aarF, a locus required for production of ubiquinone in Providencia stuartii and Escherichia coli and for expression of 2'-N-acetyltransferase in P. stuartii. J Bacteriol, 180(1):128-35. (1998)
PMid:9422602 PMCid:106858
Key Words: Primary congenital glaucoma, GLC3C locus, nuclear family, Transmission disequilibrium test
Send correspondence to: Xinghuai Sun, Eye and ENT Hospital, Department of Ophthalmology and Vision Science, Fudan University, 83 Fenyang Road, 200031, Shanghai, China, Tel:86-21-64371591, Fax:86-21-64377151, E-mail:xhsun@shmu.edu.cn