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1.  Familial Oral Microbial Imbalance and Dental Caries Occurrence in Their Children 
Objective
Develop a familial liability index for oral microbial status that reflects an imbalance of oral domains based on the presence of risk indicators in saliva, inter-proximal plaque, tongue, and throat.
Methods
Fifty-six mother-child pairs from Webster and Nicholas counties, West Virginia, USA, participated in this study. Saliva samples were assayed for mutans streptococci (MS), interproximal plaque samples for the BANA Test (BT) species, tongue swabs for BT, and throat swabs for any of the sentinel organisms (Staphylococcus aureus, Streptococcus pyogenes, and yeasts). The corresponding thresholds for a (+) risk indicator were, respectively, ≥105 CFU of MS salivary levels, one or more BT-(+) plaques (>105 CFU/mg of plaque of at least one of BT-(+) species), weak-(+) BT for a tongue swab (>104-<105), and >104 CFU/swab for any of the sentinel markers.
Results
The mean age of mothers and children was 41.6 and 14.6 years. Ninety-one % of both mothers and children had at least one (+) risk indicator. Overall, 76% of mother child-pairs had at least one (+) concordant oral microbial risk indicator. Accordingly, the relative risk (RR) of children having concordant results with their mothers was increased 1.36 (BT-plaque), 1.37 (BT-tongue), 0.94 (sentinel organisms) and 1.13 (MS) times. Principal component analysis revealed distinct sets of oral microbial risk indicators in mothers and children that correlated with dental caries prevalence rates in children.
Conclusions
Mother-child pairs shared similarities of oral microbial risk indicators that allow for the development of a liability index that can elucidate caries in the children.
PMCID: PMC3939806  PMID: 24600078
Liability Index; oral microbiology; mother; child; dental caries
2.  Adverse Oral Health and Cognitive Decline: The Health, Aging and Body Composition Study 
Background/Objectives
Periodontal disease has been associated with poorer cross-sectional cognitive function and is correlated with adverse vascular outcomes, but has received little prospective investigation in relation to cognitive decline.
Design
Analysis of a prospective cohort study.
Setting
The Health, Aging and Body Composition (Health ABC) Study
Participants and measurements
We examined the prospective association between a range of oral health parameters and cognitive function using data on 1053 participants who were administered the Modified Mini-Mental State Examination (3MS) at year 1 (baseline) and year 3, and had participated in a comprehensive periodontal examination at year 2. We investigated 3MS decline from year 3 to 5 in 947 (89.9%) participants. Covariates included age, sex, education, race, cardiovascular disease/risk and depressive symptoms.
Results
Most indicators of adverse oral health at year 2 were associated with cognitive impairment based on averaged 3MS scores <80 for years 1 and 3, but these associations were substantially confounded by education and race. Higher gingival index, a measure of gingival inflammation, at year 2 remained independently associated with this definition of cognitive impairment and, in fully adjusted analyses, was also an independent predictor of a 5+ point cognitive decline from years 3 to 5.
Conclusion
Periodontitis may be a risk factor for cognitive decline. Gingivitis is reversible and periodontitis to some degree is preventable and controllable when manifest. Therefore, further research is needed to clarify potential underlying mechanisms and oral health interventions that potentially might ameliorate cognitive decline.
doi:10.1111/jgs.12094
PMCID: PMC3578234  PMID: 23405916
cognitive decline; cognitive impairment; periodontitis; periodontal diseases; gingivitis
3.  Genome-Wide Association Study of Periodontal Health Measured by Probing Depth in Adults Ages 18−49 years 
G3: Genes|Genomes|Genetics  2013;4(2):307-314.
The etiology of chronic periodontitis clearly includes a heritable component. Our purpose was to perform a small exploratory genome-wide association study in adults ages 18–49 years to nominate genes associated with periodontal disease−related phenotypes for future consideration. Full-mouth periodontal pocket depth probing was performed on participants (N = 673), with affected status defined as two or more sextants with probing depths of 5.5 mm or greater. Two variations of this phenotype that differed in how missing teeth were treated were used in analysis. More than 1.2 million genetic markers across the genome were genotyped or imputed and tested for genetic association. We identified ten suggestive loci (p-value ≤ 1E-5), including genes/loci that have been previously implicated in chronic periodontitis: LAMA2, HAS2, CDH2, ESR1, and the genomic region on chromosome 14q21-22 between SOS2 and NIN. Moreover, we nominated novel loci not previously implicated in chronic periodontitis or related pathways, including the regions 3p22 near OSBPL10 (a lipid receptor implicated in hyperlipidemia), 4p15 near HSP90AB2P (a heat shock pseudogene), 11p15 near GVINP1 (a GTPase pseudogene), 14q31 near SEL1L (an intracellular transporter), and 18q12 in FHOD3 (an actin cytoskeleton regulator). Replication of these results in additional samples is needed. This is one of the first research efforts to identify genetic polymorphisms associated with chronic periodontitis-related phenotypes by the genome-wide association study approach. Though small, efforts such this are needed in order to nominate novel genes and generate new hypotheses for exploration and testing in future studies.
doi:10.1534/g3.113.008755
PMCID: PMC3931564  PMID: 24347629
GWAS; chronic periodontitis
4.  Exploring the genetic basis of chronic periodontitis: a genome-wide association study 
Human Molecular Genetics  2013;22(11):2312-2324.
Chronic periodontitis (CP) is a common oral disease that confers substantial systemic inflammatory and microbial burden and is a major cause of tooth loss. Here, we present the results of a genome-wide association study of CP that was carried out in a cohort of 4504 European Americans (EA) participating in the Atherosclerosis Risk in Communities (ARIC) Study (mean age—62 years, moderate CP—43% and severe CP—17%). We detected no genome-wide significant association signals for CP; however, we found suggestive evidence of association (P < 5 × 10−6) for six loci, including NIN, NPY, WNT5A for severe CP and NCR2, EMR1, 10p15 for moderate CP. Three of these loci had concordant effect size and direction in an independent sample of 656 adult EA participants of the Health, Aging, and Body Composition (Health ABC) Study. Meta-analysis pooled estimates were severe CP (n = 958 versus health: n = 1909)—NPY, rs2521634 [G]: odds ratio [OR = 1.49 (95% confidence interval (CI = 1.28–1.73, P = 3.5 × 10−7))]; moderate CP (n = 2293)—NCR2, rs7762544 [G]: OR = 1.40 (95% CI = 1.24–1.59, P = 7.5 × 10−8), EMR1, rs3826782 [A]: OR = 2.01 (95% CI = 1.52–2.65, P = 8.2 × 10−7). Canonical pathway analysis indicated significant enrichment of nervous system signaling, cellular immune response and cytokine signaling pathways. A significant interaction of NUAK1 (rs11112872, interaction P = 2.9 × 10−9) with smoking in ARIC was not replicated in Health ABC, although estimates of heritable variance in severe CP explained by all single nucleotide polymorphisms increased from 18 to 52% with the inclusion of a genome-wide interaction term with smoking. These genome-wide association results provide information on multiple candidate regions and pathways for interrogation in future genetic studies of CP.
doi:10.1093/hmg/ddt065
PMCID: PMC3652417  PMID: 23459936
5.  Effects of Smoking and Genotype on the PSR Index of Periodontal Disease in Adults Aged 18–49 
Studies have found both genetic and environmental influences on chronic periodontitis. The purpose of this study was to examine the relationships among previously identified genetic variants, smoking status, and two periodontal disease-related phenotypes (PSR1 and PSR2) in 625 Caucasian adults (aged 18–49 years). The PSR Index was used to classify participants as affected or unaffected under the PSR1 and PSR2 phenotype definitions. Using logistic regression, we found that the form of the relationship varied by single nucleotide polymorphism (SNP): For rs10457525 and rs12630931, the effects of smoking and genotype on risk were additive; whereas for rs10457526 and rs733048, smoking was not independently associated with affected status once genotype was taken into consideration. In contrast, smoking moderated the relationships of rs3870371 and rs733048 with affected status such that former and never smokers with select genotypes were at increased genetic risk. Thus, for several groups, knowledge of genotype may refine the risk prediction over that which can be determined by knowledge of smoking status alone. Future studies should replicate these findings. These findings provide the foundation for the exploration of novel pathways by which periodontitis may occur.
doi:10.3390/ijerph9082839
PMCID: PMC3447590  PMID: 23066400
adult; chronic periodontitis; genetics; genomics; smoking
6.  Hundreds of variants clustered in genomic loci and biological pathways affect human height 
Lango Allen, Hana | Estrada, Karol | Lettre, Guillaume | Berndt, Sonja I. | Weedon, Michael N. | Rivadeneira, Fernando | Willer, Cristen J. | Jackson, Anne U. | Vedantam, Sailaja | Raychaudhuri, Soumya | Ferreira, Teresa | Wood, Andrew R. | Weyant, Robert J. | Segrè, Ayellet V. | Speliotes, Elizabeth K. | Wheeler, Eleanor | Soranzo, Nicole | Park, Ju-Hyun | Yang, Jian | Gudbjartsson, Daniel | Heard-Costa, Nancy L. | Randall, Joshua C. | Qi, Lu | Smith, Albert Vernon | Mägi, Reedik | Pastinen, Tomi | Liang, Liming | Heid, Iris M. | Luan, Jian'an | Thorleifsson, Gudmar | Winkler, Thomas W. | Goddard, Michael E. | Lo, Ken Sin | Palmer, Cameron | Workalemahu, Tsegaselassie | Aulchenko, Yurii S. | Johansson, Åsa | Zillikens, M.Carola | Feitosa, Mary F. | Esko, Tõnu | Johnson, Toby | Ketkar, Shamika | Kraft, Peter | Mangino, Massimo | Prokopenko, Inga | Absher, Devin | Albrecht, Eva | Ernst, Florian | Glazer, Nicole L. | Hayward, Caroline | Hottenga, Jouke-Jan | Jacobs, Kevin B. | Knowles, Joshua W. | Kutalik, Zoltán | Monda, Keri L. | Polasek, Ozren | Preuss, Michael | Rayner, Nigel W. | Robertson, Neil R. | Steinthorsdottir, Valgerdur | Tyrer, Jonathan P. | Voight, Benjamin F. | Wiklund, Fredrik | Xu, Jianfeng | Zhao, Jing Hua | Nyholt, Dale R. | Pellikka, Niina | Perola, Markus | Perry, John R.B. | Surakka, Ida | Tammesoo, Mari-Liis | Altmaier, Elizabeth L. | Amin, Najaf | Aspelund, Thor | Bhangale, Tushar | Boucher, Gabrielle | Chasman, Daniel I. | Chen, Constance | Coin, Lachlan | Cooper, Matthew N. | Dixon, Anna L. | Gibson, Quince | Grundberg, Elin | Hao, Ke | Junttila, M. Juhani | Kaplan, Lee M. | Kettunen, Johannes | König, Inke R. | Kwan, Tony | Lawrence, Robert W. | Levinson, Douglas F. | Lorentzon, Mattias | McKnight, Barbara | Morris, Andrew P. | Müller, Martina | Ngwa, Julius Suh | Purcell, Shaun | Rafelt, Suzanne | Salem, Rany M. | Salvi, Erika | Sanna, Serena | Shi, Jianxin | Sovio, Ulla | Thompson, John R. | Turchin, Michael C. | Vandenput, Liesbeth | Verlaan, Dominique J. | Vitart, Veronique | White, Charles C. | Ziegler, Andreas | Almgren, Peter | Balmforth, Anthony J. | Campbell, Harry | Citterio, Lorena | De Grandi, Alessandro | Dominiczak, Anna | Duan, Jubao | Elliott, Paul | Elosua, Roberto | Eriksson, Johan G. | Freimer, Nelson B. | Geus, Eco J.C. | Glorioso, Nicola | Haiqing, Shen | Hartikainen, Anna-Liisa | Havulinna, Aki S. | Hicks, Andrew A. | Hui, Jennie | Igl, Wilmar | Illig, Thomas | Jula, Antti | Kajantie, Eero | Kilpeläinen, Tuomas O. | Koiranen, Markku | Kolcic, Ivana | Koskinen, Seppo | Kovacs, Peter | Laitinen, Jaana | Liu, Jianjun | Lokki, Marja-Liisa | Marusic, Ana | Maschio, Andrea | Meitinger, Thomas | Mulas, Antonella | Paré, Guillaume | Parker, Alex N. | Peden, John F. | Petersmann, Astrid | Pichler, Irene | Pietiläinen, Kirsi H. | Pouta, Anneli | Ridderstråle, Martin | Rotter, Jerome I. | Sambrook, Jennifer G. | Sanders, Alan R. | Schmidt, Carsten Oliver | Sinisalo, Juha | Smit, Jan H. | Stringham, Heather M. | Walters, G.Bragi | Widen, Elisabeth | Wild, Sarah H. | Willemsen, Gonneke | Zagato, Laura | Zgaga, Lina | Zitting, Paavo | Alavere, Helene | Farrall, Martin | McArdle, Wendy L. | Nelis, Mari | Peters, Marjolein J. | Ripatti, Samuli | van Meurs, Joyce B.J. | Aben, Katja K. | Ardlie, Kristin G | Beckmann, Jacques S. | Beilby, John P. | Bergman, Richard N. | Bergmann, Sven | Collins, Francis S. | Cusi, Daniele | den Heijer, Martin | Eiriksdottir, Gudny | Gejman, Pablo V. | Hall, Alistair S. | Hamsten, Anders | Huikuri, Heikki V. | Iribarren, Carlos | Kähönen, Mika | Kaprio, Jaakko | Kathiresan, Sekar | Kiemeney, Lambertus | Kocher, Thomas | Launer, Lenore J. | Lehtimäki, Terho | Melander, Olle | Mosley, Tom H. | Musk, Arthur W. | Nieminen, Markku S. | O'Donnell, Christopher J. | Ohlsson, Claes | Oostra, Ben | Palmer, Lyle J. | Raitakari, Olli | Ridker, Paul M. | Rioux, John D. | Rissanen, Aila | Rivolta, Carlo | Schunkert, Heribert | Shuldiner, Alan R. | Siscovick, David S. | Stumvoll, Michael | Tönjes, Anke | Tuomilehto, Jaakko | van Ommen, Gert-Jan | Viikari, Jorma | Heath, Andrew C. | Martin, Nicholas G. | Montgomery, Grant W. | Province, Michael A. | Kayser, Manfred | Arnold, Alice M. | Atwood, Larry D. | Boerwinkle, Eric | Chanock, Stephen J. | Deloukas, Panos | Gieger, Christian | Grönberg, Henrik | Hall, Per | Hattersley, Andrew T. | Hengstenberg, Christian | Hoffman, Wolfgang | Lathrop, G.Mark | Salomaa, Veikko | Schreiber, Stefan | Uda, Manuela | Waterworth, Dawn | Wright, Alan F. | Assimes, Themistocles L. | Barroso, Inês | Hofman, Albert | Mohlke, Karen L. | Boomsma, Dorret I. | Caulfield, Mark J. | Cupples, L.Adrienne | Erdmann, Jeanette | Fox, Caroline S. | Gudnason, Vilmundur | Gyllensten, Ulf | Harris, Tamara B. | Hayes, Richard B. | Jarvelin, Marjo-Riitta | Mooser, Vincent | Munroe, Patricia B. | Ouwehand, Willem H. | Penninx, Brenda W. | Pramstaller, Peter P. | Quertermous, Thomas | Rudan, Igor | Samani, Nilesh J. | Spector, Timothy D. | Völzke, Henry | Watkins, Hugh | Wilson, James F. | Groop, Leif C. | Haritunians, Talin | Hu, Frank B. | Kaplan, Robert C. | Metspalu, Andres | North, Kari E. | Schlessinger, David | Wareham, Nicholas J. | Hunter, David J. | O'Connell, Jeffrey R. | Strachan, David P. | Wichmann, H.-Erich | Borecki, Ingrid B. | van Duijn, Cornelia M. | Schadt, Eric E. | Thorsteinsdottir, Unnur | Peltonen, Leena | Uitterlinden, André | Visscher, Peter M. | Chatterjee, Nilanjan | Loos, Ruth J.F. | Boehnke, Michael | McCarthy, Mark I. | Ingelsson, Erik | Lindgren, Cecilia M. | Abecasis, Gonçalo R. | Stefansson, Kari | Frayling, Timothy M. | Hirschhorn, Joel N
Nature  2010;467(7317):832-838.
Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence phenotype. Genome-wide association (GWA) studies have identified >600 variants associated with human traits1, but these typically explain small fractions of phenotypic variation, raising questions about the utility of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait2,3. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P=0.016), and that underlie skeletal growth defects (P<0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants, and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented amongst variants that alter amino acid structure of proteins and expression levels of nearby genes. Our data explain ∼10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to ∼16% of phenotypic variation (∼20% of heritable variation). Although additional approaches are needed to fully dissect the genetic architecture of polygenic human traits, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
doi:10.1038/nature09410
PMCID: PMC2955183  PMID: 20881960
7.  Human Telomere Length Correlates to the Size of the Associated Chromosome Arm 
PLoS ONE  2009;4(6):e6013.
The majority of human telomere length studies have focused on the overall length of telomeres within a cell. In fact, very few studies have examined telomere length for individual chromosome arms. The objective of this study was to examine the relationship between chromosome arm size and the relative length of the associated telomere. Quantitative Fluorescence In Situ Hybridization (Q-FISH) was used to measure the relative telomere length of each chromosome arm in metaphases from cultured lymphocytes of 17 individuals. A statistically significant positive correlation (r = 0.6) was found between telomere length and the size of the associated chromosome arm, which was estimated based on megabase pair measurements from http://www.ncbi.nlm.nih.gov/projects/mapview/.
doi:10.1371/journal.pone.0006013
PMCID: PMC2695537  PMID: 19547752
8.  Cryptic Subtelomeric Rearrangements and X Chromosome Mosaicism: A Study of 565 Apparently Normal Individuals with Fluorescent In Situ Hybridization 
PLoS ONE  2009;4(6):e5855.
Five percent of patients with unexplained mental retardation have been attributed to cryptic unbalanced subtelomeric rearrangements. Half of these affected individuals have inherited the rearrangement from a parent who is a carrier for a balanced translocation. However, the frequency of carriers for cryptic balanced translocations is unknown. To determine this frequency, 565 phenotypically normal unrelated individuals were examined for balanced subtelomeric rearrangements using Fluorescent In Situ hybridization (FISH) probes for all subtelomere regions. While no balanced subtelomeric rearrangements were identified, three females in this study were determined to be mosaic for the X chromosome. Mosaicism for XXX cell lines were observed in the lymphocyte cultures of 3 in 379 women (0.8%), which is a higher frequency than the 1 in 1000 (0.1%) reported for sex chromosome aneuploidies. Our findings suggest that numerical abnormalities of the X chromosome are more common in females than previously reported. Based on a review of the literature, the incidence of cryptic translocation carriers is estimated to be approximately 1/8,000, more than ten-fold higher than the frequency of visible reciprocal translocations.
doi:10.1371/journal.pone.0005855
PMCID: PMC2688762  PMID: 19516895
9.  Study protocol of the Center for Oral Health Research in Appalachia (COHRA) etiology study 
BMC Oral Health  2008;8:18.
Background
People in Appalachia experience some of the worst oral health in the United States. To develop effective intervention and prevention strategies in Appalachia, we must understand the complex relationships among the contributing factors and how they affect the etiology of oral diseases. To date, no such comprehensive analysis has been conducted. This report summarizes the characteristics of the sample and describes the protocol of a study determining contributions of individual, family, and community factors to oral diseases in Appalachian children and their relatives.
Methods/Design
Families participated in a comprehensive assessment protocol involving interviews, questionnaires, a clinical oral health assessment, a microbiological assessment, and collection of DNA. The design of the study is cross-sectional.
Conclusion
Due to its multilevel design and large, family-based sample, this study has the potential to greatly advance our understanding of factors that contribute to oral health in Appalachian children.
doi:10.1186/1472-6831-8-18
PMCID: PMC2443132  PMID: 18522740
10.  Using Biometrics for Participant Identification in a Research Study: a Case Report 
This paper illustrates the use of biometrics through the application of an iris-based biometrics system for identifying twins and their parents in a longitudinal research study. It explores the use of biometrics (science of measuring physical or anatomical characteristics of individuals) as a technology for correct identification of individuals during longitudinal studies to help ensure data fidelity. Examples of these circumstances include longitudinal epidemiological and genetic studies, clinical trials, and multicenter collaborative studies where accurate identification of subjects over time can be difficult when the subject may be young or an unreliable source of identification information. The use of technology can automate the process of subject identification thereby reducing the need to depend on subject recall during repeated visits thus helping to ensure data quality. This case report provides insights that may serve as useful hints for those responsible for planning system implementation that involves participants' authentication that would require a more secure form of identification.
doi:10.1197/jamia.M1793
PMCID: PMC1447546  PMID: 16357359
11.  Genome-wide association Scan of dental caries in the permanent dentition 
BMC Oral Health  2012;12:57.
Background
Over 90% of adults aged 20 years or older with permanent teeth have suffered from dental caries leading to pain, infection, or even tooth loss. Although caries prevalence has decreased over the past decade, there are still about 23% of dentate adults who have untreated carious lesions in the US. Dental caries is a complex disorder affected by both individual susceptibility and environmental factors. Approximately 35-55% of caries phenotypic variation in the permanent dentition is attributable to genes, though few specific caries genes have been identified. Therefore, we conducted the first genome-wide association study (GWAS) to identify genes affecting susceptibility to caries in adults.
Methods
Five independent cohorts were included in this study, totaling more than 7000 participants. For each participant, dental caries was assessed and genetic markers (single nucleotide polymorphisms, SNPs) were genotyped or imputed across the entire genome. Due to the heterogeneity among the five cohorts regarding age, genotyping platform, quality of dental caries assessment, and study design, we first conducted genome-wide association (GWA) analyses on each of the five independent cohorts separately. We then performed three meta-analyses to combine results for: (i) the comparatively younger, Appalachian cohorts (N = 1483) with well-assessed caries phenotype, (ii) the comparatively older, non-Appalachian cohorts (N = 5960) with inferior caries phenotypes, and (iii) all five cohorts (N = 7443). Top ranking genetic loci within and across meta-analyses were scrutinized for biologically plausible roles on caries.
Results
Different sets of genes were nominated across the three meta-analyses, especially between the younger and older age cohorts. In general, we identified several suggestive loci (P-value ≤ 10E-05) within or near genes with plausible biological roles for dental caries, including RPS6KA2 and PTK2B, involved in p38-depenedent MAPK signaling, and RHOU and FZD1, involved in the Wnt signaling cascade. Both of these pathways have been implicated in dental caries. ADMTS3 and ISL1 are involved in tooth development, and TLR2 is involved in immune response to oral pathogens.
Conclusions
As the first GWAS for dental caries in adults, this study nominated several novel caries genes for future study, which may lead to better understanding of cariogenesis, and ultimately, to improved disease predictions, prevention, and/or treatment.
doi:10.1186/1472-6831-12-57
PMCID: PMC3574042  PMID: 23259602
Dental caries; Genetics; Genome wide association; Permanent dentition; Genomics
12.  Heritable patterns of tooth decay in the permanent dentition: principal components and factor analyses 
BMC Oral Health  2012;12:7.
Background
Dental caries is the result of a complex interplay among environmental, behavioral, and genetic factors, with distinct patterns of decay likely due to specific etiologies. Therefore, global measures of decay, such as the DMFS index, may not be optimal for identifying risk factors that manifest as specific decay patterns, especially if the risk factors such as genetic susceptibility loci have small individual effects. We used two methods to extract patterns of decay from surface-level caries data in order to generate novel phenotypes with which to explore the genetic regulation of caries.
Methods
The 128 tooth surfaces of the permanent dentition were scored as carious or not by intra-oral examination for 1,068 participants aged 18 to 75 years from 664 biological families. Principal components analysis (PCA) and factor analysis (FA), two methods of identifying underlying patterns without a priori surface classifications, were applied to our data.
Results
The three strongest caries patterns identified by PCA recaptured variation represented by DMFS index (correlation, r = 0.97), pit and fissure surface caries (r = 0.95), and smooth surface caries (r = 0.89). However, together, these three patterns explained only 37% of the variability in the data, indicating that a priori caries measures are insufficient for fully quantifying caries variation. In comparison, the first pattern identified by FA was strongly correlated with pit and fissure surface caries (r = 0.81), but other identified patterns, including a second pattern representing caries of the maxillary incisors, were not representative of any previously defined caries indices. Some patterns identified by PCA and FA were heritable (h2 = 30-65%, p = 0.043-0.006), whereas other patterns were not, indicating both genetic and non-genetic etiologies of individual decay patterns.
Conclusions
This study demonstrates the use of decay patterns as novel phenotypes to assist in understanding the multifactorial nature of dental caries.
doi:10.1186/1472-6831-12-7
PMCID: PMC3328249  PMID: 22405185
Dental caries genetics; Heritability; Permanent dentition; Pit and fissure surfaces; Smooth surfaces; Tooth surfaces; Principal components analysis; Factor analysis; Patterns of tooth decay; Patterns of dental caries
13.  Genome-Wide Association Study Identifies Four Loci Associated with Eruption of Permanent Teeth 
PLoS Genetics  2011;7(9):e1002275.
The sequence and timing of permanent tooth eruption is thought to be highly heritable and can have important implications for the risk of malocclusion, crowding, and periodontal disease. We conducted a genome-wide association study of number of permanent teeth erupted between age 6 and 14 years, analyzed as age-adjusted standard deviation score averaged over multiple time points, based on childhood records for 5,104 women from the Danish National Birth Cohort. Four loci showed association at P<5×10−8 and were replicated in four independent study groups from the United States and Denmark with a total of 3,762 individuals; all combined P-values were below 10−11. Two loci agreed with previous findings in primary tooth eruption and were also known to influence height and breast cancer, respectively. The two other loci pointed to genomic regions without any previous significant genome-wide association study results. The intronic SNP rs7924176 in ADK could be linked to gene expression in monocytes. The combined effect of the four genetic variants was most pronounced between age 10 and 12 years, where children with 6 to 8 delayed tooth eruption alleles had on average 3.5 (95% confidence interval: 2.9–4.1) fewer permanent teeth than children with 0 or 1 of these alleles.
Author Summary
While genome-wide association studies (GWAS) initially focused on the disease under investigation, additional findings in secondary traits have shown further benefits of having extensive phenotype data at hand. Using records from the nationwide dental registry for children and genotype data from two GWAS, we were able to identify four genomic loci associated with permanent tooth eruption in children. Two of the identified genomic regions had no previous GWAS findings, whereas two loci were reported in the context of primary dentition. A follow-up in an on-going GWAS showed that rs7924176 also plays a substantial role in primary dentition. During the age period of permanent tooth eruption many important developmental processes take place. Thus, we suggest following up the four reported SNPs in other growth-related traits to further elucidate the genetic background of maturation.
doi:10.1371/journal.pgen.1002275
PMCID: PMC3169538  PMID: 21931568
14.  Detection of Streptococcus mutans Genomic DNA in Human DNA Samples Extracted from Saliva and Blood 
ISRN dentistry  2011;2011:543561.
Caries is a multifactorial disease, and studies aiming to unravel the factors modulating its etiology must consider all known predisposing factors. One major factor is bacterial colonization, and Streptococcus mutans is the main microorganism associated with the initiation of the disease. In our studies, we have access to DNA samples extracted from human saliva and blood. In this report, we tested a real-time PCR assay developed to detect copies of genomic DNA from Streptococcus mutans in 1,424 DNA samples from humans. Our results suggest that we can determine the presence of genomic DNA copies of Streptococcus mutans in both DNA samples from caries-free and caries-affected individuals. However, we were not able to detect the presence of genomic DNA copies of Streptococcus mutans in any DNA samples extracted from peripheral blood, which suggests the assay may not be sensitive enough for this goal. Values of the threshold cycle of the real-time PCR reaction correlate with higher levels of caries experience in children, but this correlation could not be detected for adults.
doi:10.5402/2011/543561
PMCID: PMC3128887  PMID: 21731912
15.  Association analyses of 249,796 individuals reveal eighteen new loci associated with body mass index 
Speliotes, Elizabeth K. | Willer, Cristen J. | Berndt, Sonja I. | Monda, Keri L. | Thorleifsson, Gudmar | Jackson, Anne U. | Allen, Hana Lango | Lindgren, Cecilia M. | Luan, Jian’an | Mägi, Reedik | Randall, Joshua C. | Vedantam, Sailaja | Winkler, Thomas W. | Qi, Lu | Workalemahu, Tsegaselassie | Heid, Iris M. | Steinthorsdottir, Valgerdur | Stringham, Heather M. | Weedon, Michael N. | Wheeler, Eleanor | Wood, Andrew R. | Ferreira, Teresa | Weyant, Robert J. | Segré, Ayellet V. | Estrada, Karol | Liang, Liming | Nemesh, James | Park, Ju-Hyun | Gustafsson, Stefan | Kilpeläinen, Tuomas O. | Yang, Jian | Bouatia-Naji, Nabila | Esko, Tõnu | Feitosa, Mary F. | Kutalik, Zoltán | Mangino, Massimo | Raychaudhuri, Soumya | Scherag, Andre | Smith, Albert Vernon | Welch, Ryan | Zhao, Jing Hua | Aben, Katja K. | Absher, Devin M. | Amin, Najaf | Dixon, Anna L. | Fisher, Eva | Glazer, Nicole L. | Goddard, Michael E. | Heard-Costa, Nancy L. | Hoesel, Volker | Hottenga, Jouke-Jan | Johansson, Åsa | Johnson, Toby | Ketkar, Shamika | Lamina, Claudia | Li, Shengxu | Moffatt, Miriam F. | Myers, Richard H. | Narisu, Narisu | Perry, John R.B. | Peters, Marjolein J. | Preuss, Michael | Ripatti, Samuli | Rivadeneira, Fernando | Sandholt, Camilla | Scott, Laura J. | Timpson, Nicholas J. | Tyrer, Jonathan P. | van Wingerden, Sophie | Watanabe, Richard M. | White, Charles C. | Wiklund, Fredrik | Barlassina, Christina | Chasman, Daniel I. | Cooper, Matthew N. | Jansson, John-Olov | Lawrence, Robert W. | Pellikka, Niina | Prokopenko, Inga | Shi, Jianxin | Thiering, Elisabeth | Alavere, Helene | Alibrandi, Maria T. S. | Almgren, Peter | Arnold, Alice M. | Aspelund, Thor | Atwood, Larry D. | Balkau, Beverley | Balmforth, Anthony J. | Bennett, Amanda J. | Ben-Shlomo, Yoav | Bergman, Richard N. | Bergmann, Sven | Biebermann, Heike | Blakemore, Alexandra I.F. | Boes, Tanja | Bonnycastle, Lori L. | Bornstein, Stefan R. | Brown, Morris J. | Buchanan, Thomas A. | Busonero, Fabio | Campbell, Harry | Cappuccio, Francesco P. | Cavalcanti-Proença, Christine | Chen, Yii-Der Ida | Chen, Chih-Mei | Chines, Peter S. | Clarke, Robert | Coin, Lachlan | Connell, John | Day, Ian N.M. | Heijer, Martin den | Duan, Jubao | Ebrahim, Shah | Elliott, Paul | Elosua, Roberto | Eiriksdottir, Gudny | Erdos, Michael R. | Eriksson, Johan G. | Facheris, Maurizio F. | Felix, Stephan B. | Fischer-Posovszky, Pamela | Folsom, Aaron R. | Friedrich, Nele | Freimer, Nelson B. | Fu, Mao | Gaget, Stefan | Gejman, Pablo V. | Geus, Eco J.C. | Gieger, Christian | Gjesing, Anette P. | Goel, Anuj | Goyette, Philippe | Grallert, Harald | Gräßler, Jürgen | Greenawalt, Danielle M. | Groves, Christopher J. | Gudnason, Vilmundur | Guiducci, Candace | Hartikainen, Anna-Liisa | Hassanali, Neelam | Hall, Alistair S. | Havulinna, Aki S. | Hayward, Caroline | Heath, Andrew C. | Hengstenberg, Christian | Hicks, Andrew A. | Hinney, Anke | Hofman, Albert | Homuth, Georg | Hui, Jennie | Igl, Wilmar | Iribarren, Carlos | Isomaa, Bo | Jacobs, Kevin B. | Jarick, Ivonne | Jewell, Elizabeth | John, Ulrich | Jørgensen, Torben | Jousilahti, Pekka | Jula, Antti | Kaakinen, Marika | Kajantie, Eero | Kaplan, Lee M. | Kathiresan, Sekar | Kettunen, Johannes | Kinnunen, Leena | Knowles, Joshua W. | Kolcic, Ivana | König, Inke R. | Koskinen, Seppo | Kovacs, Peter | Kuusisto, Johanna | Kraft, Peter | Kvaløy, Kirsti | Laitinen, Jaana | Lantieri, Olivier | Lanzani, Chiara | Launer, Lenore J. | Lecoeur, Cecile | Lehtimäki, Terho | Lettre, Guillaume | Liu, Jianjun | Lokki, Marja-Liisa | Lorentzon, Mattias | Luben, Robert N. | Ludwig, Barbara | Manunta, Paolo | Marek, Diana | Marre, Michel | Martin, Nicholas G. | McArdle, Wendy L. | McCarthy, Anne | McKnight, Barbara | Meitinger, Thomas | Melander, Olle | Meyre, David | Midthjell, Kristian | Montgomery, Grant W. | Morken, Mario A. | Morris, Andrew P. | Mulic, Rosanda | Ngwa, Julius S. | Nelis, Mari | Neville, Matt J. | Nyholt, Dale R. | O’Donnell, Christopher J. | O’Rahilly, Stephen | Ong, Ken K. | Oostra, Ben | Paré, Guillaume | Parker, Alex N. | Perola, Markus | Pichler, Irene | Pietiläinen, Kirsi H. | Platou, Carl G.P. | Polasek, Ozren | Pouta, Anneli | Rafelt, Suzanne | Raitakari, Olli | Rayner, Nigel W. | Ridderstråle, Martin | Rief, Winfried | Ruokonen, Aimo | Robertson, Neil R. | Rzehak, Peter | Salomaa, Veikko | Sanders, Alan R. | Sandhu, Manjinder S. | Sanna, Serena | Saramies, Jouko | Savolainen, Markku J. | Scherag, Susann | Schipf, Sabine | Schreiber, Stefan | Schunkert, Heribert | Silander, Kaisa | Sinisalo, Juha | Siscovick, David S. | Smit, Jan H. | Soranzo, Nicole | Sovio, Ulla | Stephens, Jonathan | Surakka, Ida | Swift, Amy J. | Tammesoo, Mari-Liis | Tardif, Jean-Claude | Teder-Laving, Maris | Teslovich, Tanya M. | Thompson, John R. | Thomson, Brian | Tönjes, Anke | Tuomi, Tiinamaija | van Meurs, Joyce B.J. | van Ommen, Gert-Jan | Vatin, Vincent | Viikari, Jorma | Visvikis-Siest, Sophie | Vitart, Veronique | Vogel, Carla I. G. | Voight, Benjamin F. | Waite, Lindsay L. | Wallaschofski, Henri | Walters, G. Bragi | Widen, Elisabeth | Wiegand, Susanna | Wild, Sarah H. | Willemsen, Gonneke | Witte, Daniel R. | Witteman, Jacqueline C. | Xu, Jianfeng | Zhang, Qunyuan | Zgaga, Lina | Ziegler, Andreas | Zitting, Paavo | Beilby, John P. | Farooqi, I. Sadaf | Hebebrand, Johannes | Huikuri, Heikki V. | James, Alan L. | Kähönen, Mika | Levinson, Douglas F. | Macciardi, Fabio | Nieminen, Markku S. | Ohlsson, Claes | Palmer, Lyle J. | Ridker, Paul M. | Stumvoll, Michael | Beckmann, Jacques S. | Boeing, Heiner | Boerwinkle, Eric | Boomsma, Dorret I. | Caulfield, Mark J. | Chanock, Stephen J. | Collins, Francis S. | Cupples, L. Adrienne | Smith, George Davey | Erdmann, Jeanette | Froguel, Philippe | Grönberg, Henrik | Gyllensten, Ulf | Hall, Per | Hansen, Torben | Harris, Tamara B. | Hattersley, Andrew T. | Hayes, Richard B. | Heinrich, Joachim | Hu, Frank B. | Hveem, Kristian | Illig, Thomas | Jarvelin, Marjo-Riitta | Kaprio, Jaakko | Karpe, Fredrik | Khaw, Kay-Tee | Kiemeney, Lambertus A. | Krude, Heiko | Laakso, Markku | Lawlor, Debbie A. | Metspalu, Andres | Munroe, Patricia B. | Ouwehand, Willem H. | Pedersen, Oluf | Penninx, Brenda W. | Peters, Annette | Pramstaller, Peter P. | Quertermous, Thomas | Reinehr, Thomas | Rissanen, Aila | Rudan, Igor | Samani, Nilesh J. | Schwarz, Peter E.H. | Shuldiner, Alan R. | Spector, Timothy D. | Tuomilehto, Jaakko | Uda, Manuela | Uitterlinden, André | Valle, Timo T. | Wabitsch, Martin | Waeber, Gérard | Wareham, Nicholas J. | Watkins, Hugh | Wilson, James F. | Wright, Alan F. | Zillikens, M. Carola | Chatterjee, Nilanjan | McCarroll, Steven A. | Purcell, Shaun | Schadt, Eric E. | Visscher, Peter M. | Assimes, Themistocles L. | Borecki, Ingrid B. | Deloukas, Panos | Fox, Caroline S. | Groop, Leif C. | Haritunians, Talin | Hunter, David J. | Kaplan, Robert C. | Mohlke, Karen L. | O’Connell, Jeffrey R. | Peltonen, Leena | Schlessinger, David | Strachan, David P. | van Duijn, Cornelia M. | Wichmann, H.-Erich | Frayling, Timothy M. | Thorsteinsdottir, Unnur | Abecasis, Gonçalo R. | Barroso, Inês | Boehnke, Michael | Stefansson, Kari | North, Kari E. | McCarthy, Mark I. | Hirschhorn, Joel N. | Ingelsson, Erik | Loos, Ruth J.F.
Nature genetics  2010;42(11):937-948.
Obesity is globally prevalent and highly heritable, but the underlying genetic factors remain largely elusive. To identify genetic loci for obesity-susceptibility, we examined associations between body mass index (BMI) and ~2.8 million SNPs in up to 123,865 individuals, with targeted follow-up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity-susceptibility loci and identified 18 new loci associated with BMI (P<5×10−8), one of which includes a copy number variant near GPRC5B. Some loci (MC4R, POMC, SH2B1, BDNF) map near key hypothalamic regulators of energy balance, and one is near GIPR, an incretin receptor. Furthermore, genes in other newly-associated loci may provide novel insights into human body weight regulation.
doi:10.1038/ng.686
PMCID: PMC3014648  PMID: 20935630
16.  Detection of Streptococcus mutans Genomic DNA in Human DNA Samples Extracted from Saliva and Blood 
ISRN Dentistry  2011;2011:543561.
Caries is a multifactorial disease, and studies aiming to unravel the factors modulating its etiology must consider all known predisposing factors. One major factor is bacterial colonization, and Streptococcus mutans is the main microorganism associated with the initiation of the disease. In our studies, we have access to DNA samples extracted from human saliva and blood. In this report, we tested a real-time PCR assay developed to detect copies of genomic DNA from Streptococcus mutans in 1,424 DNA samples from humans. Our results suggest that we can determine the presence of genomic DNA copies of Streptococcus mutans in both DNA samples from caries-free and caries-affected individuals. However, we were not able to detect the presence of genomic DNA copies of Streptococcus mutans in any DNA samples extracted from peripheral blood, which suggests the assay may not be sensitive enough for this goal. Values of the threshold cycle of the real-time PCR reaction correlate with higher levels of caries experience in children, but this correlation could not be detected for adults.
doi:10.5402/2011/543561
PMCID: PMC3128887  PMID: 21731912
17.  Use of 16S ribosomal RNA gene analyses to characterize the bacterial signature associated with poor oral health in West Virginia 
BMC Oral Health  2011;11:7.
Background
West Virginia has the worst oral health in the United States, but the reasons for this are unclear. This pilot study explored the etiology of this disparity using culture-independent analyses to identify bacterial species associated with oral disease.
Methods
Bacteria in subgingival plaque samples from twelve participants in two independent West Virginia dental-related studies were characterized using 16S rRNA gene sequencing and Human Oral Microbe Identification Microarray (HOMIM) analysis. Unifrac analysis was used to characterize phylogenetic differences between bacterial communities obtained from plaque of participants with low or high oral disease, which was further evaluated using clustering and Principal Coordinate Analysis.
Results
Statistically different bacterial signatures (P < 0.001) were identified in subgingival plaque of individuals with low or high oral disease in West Virginia based on 16S rRNA gene sequencing. Low disease contained a high frequency of Veillonella and Streptococcus, with a moderate number of Capnocytophaga. High disease exhibited substantially increased bacterial diversity and included a large proportion of Clostridiales cluster bacteria (Selenomonas, Eubacterium, Dialister). Phylogenetic trees constructed using 16S rRNA gene sequencing revealed that Clostridiales were repeated colonizers in plaque associated with high oral disease, providing evidence that the oral environment is somehow influencing the bacterial signature linked to disease.
Conclusions
Culture-independent analyses identified an atypical bacterial signature associated with high oral disease in West Virginians and provided evidence that the oral environment influenced this signature. Both findings provide insight into the etiology of the oral disparity in West Virginia.
doi:10.1186/1472-6831-11-7
PMCID: PMC3061962  PMID: 21362199

Results 1-17 (17)