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GENETIC POLYMORPHISM PRESENTED BY DR. M. SHIVA SHANKER IST YEAR POST GRADUATE STUDENT , DEPT OF PERIODONTICS, MAMATA DENTAL COLLEGE.
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Genetic polymorphism

Sep 10, 2014

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Page 1: Genetic polymorphism

GENETIC POLYMORPHISM

PRESENTED BYDR. M. SHIVA SHANKER

IST YEAR POST GRADUATE STUDENT ,DEPT OF PERIODONTICS, MAMATA DENTAL COLLEGE.

Page 2: Genetic polymorphism

CONTENTS

• Introduction• Genetics • Terminologies• Types of genetic disorders

Single gene defectsMultifactorial diseases

• Methods of genetic analysis – genetic study designs

• Human gene polymorphisms• Various type of polymorphisms and

their relationship to the periodontal disease

• Proving a disease/polymorphism relationship

• Future application of genetic information

• Conclusion

Page 3: Genetic polymorphism

INTRODUCTION

• The science of genetics is concerned with the inheritance of traits, whether normal or abnormal, and with the interaction of genes and the environment.

• Individuals may respond differently to common environmental challenges, and this differential response is influenced by the individual’s genetic profile.

• The genetic origin of a disease is either partly or wholly due to abnormalities within the genetic code.

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CELL

• Cells are the basic building blocks of all living things. • The human body is composed of trillions of cells. They provide structure for

the body• Cells consists of various parts

Page 5: Genetic polymorphism

Nucleus

• The nucleus serves as the cell’s command center, sending directions to the cell to grow,mature, divide, or die. • The nucleus is surrounded by a membrane called the nuclear envelope,which protects the DNA and separates the nucleus from the rest of the cell.

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CHROMOSOME• In the nucleus of each cell, the DNA

molecule is packaged into thread-like structures called chromosomes.• Each chromosome has a constriction point

called the centromere.• centromere divides the chromosome into

two sections, or “arms.”• The location of the centromere on each

chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.

Page 7: Genetic polymorphism

DNA

• DNA consists of chemically linked sequences of nucleotides; these are the "building blocks" of the DNA and always contain a nitrogenous base.

• Four nitrogenous bases exist: adenine (a), guanine (g), cytosine (q and thymine (t).

• The bases are linked to a sugar (2-deoxyribose), where a phosphate group is also added.

Page 8: Genetic polymorphism

DNA contain the genetic code .The genetic code is read in groups of three nucleotide ,and called as “codon”. • Coding region• Promoter region

Page 9: Genetic polymorphism

• Variant forms of a gene that can occupy a specific chromosal site (locus) are called alleles.

• when different alleles of a given gene co-ex ist in the human population, we speak about genetic polymorphisms.

• An alteration that changes in single point base pair is called a point mutation

• The most common class of point mu tations is the transition, comprising the substitution of one nucleotide with another

• Termed as single nucleotide polymorphism

Page 10: Genetic polymorphism

TERMINOLOGIES:

• Allele: alternate forms of a given gene differing in DNA sequence assumed to arise by mutation and affecting the function of a single product.

• Chromosome: a nuclear structure carrying genetic information arranged in a linear sequence.

• Genetic code: the consecutive nucleotide triplets that specify the sequence of aminoacids for protein synthesis.

• Genome: a term used to refer to all the genes carried by an individual or cell

Page 11: Genetic polymorphism

• Genotype: the genetic makeup of an organism or cell distinct from its expressed features.• Locus: the physical location a gene occupies within a chromosome or portion of genomic

DNA.• Linkage: the tendency for certain genes to be inherited together due to their presence on

the same chromosome.• Linkage disequilibrium: occurrence of some genes together more often than would be

expected by random distribution• Polymorphism: when a mutation increases to a level involving more than 1% of the

population, it is referred to as a polymorphism, which merely means that there are multiple forms of the specific nucleotide sequence that may be found at the genetic locus.

• Single nucleotide polymorphism (snp): common, but minute, variations that occur in human DNA at a frequency of one in every 1,000 bases. These variations can be used to track inheritance in families. SNP is pronounced, "snip".

Page 12: Genetic polymorphism

TYPES OF GENETIC DEFECTS

• Mendelian disorders (single-gene defects)• Non-mendelian disorders (multifactorial disorders)

Page 13: Genetic polymorphism

SIMPLE Vs MULTIFACTORIAL GENETIC TRAITS

SIMPLE MENDELIAN TRAITS• Mutations of critical genes alter

gene function causing disease phenotype.

• Mutations of a specific gene are typically rare (<1%).

• Inherited in a predictable pattern-simple mendelian fashion.

MULTIFACTORIAL GENETIC TRAITS • Complex diseases result from interactive

effect of multiple gene products modulated by environmental agents.

• Genes responsible are not altered (mutated) instead they exist in multiple different forms(alleles) which differ in terms of function-functional polymorphism.

• Polymorphisms can be enhanced by environmental agents

• Difficult to estimate the degree of interaction between a range of genotypes & environment.

Page 14: Genetic polymorphism

METHODS OF GENETIC ANALYSIS

• Evidence for a genetic predisposition to periodontitis comes from four areas of research:

1. The study of inherited diseases and genetic syndromes2. Family studies3. Twin studies4. Population studiesLinkage and association studies• They are used to map disease alleles to specific regions on chromosomes.

Page 15: Genetic polymorphism

HUMAN GENE POLYMORPHISM

• When a nucleotide change is very rare, and not present in many individuals, it is often called a mutation. In contrast to mutations, genetic polymorphisms are usually considered normal variants in population. When a specific allele occurs in at least 1% of the population, it is said to be a genetic polymorphism.

Page 16: Genetic polymorphism

Alters the triplet codon codon changes still code for the

same amino acid. Alters aminoacid composition

Change of nucleotide

Allelic variant

Page 17: Genetic polymorphism

POLYMORPHISM

• Polymorphisms of human genes occur at one or more of the following

Page 18: Genetic polymorphism

TYPES OF POLYMORPHISMS

SINGLE NUCLEOTIDE POLYMORPHISMS (SNP)• The most common form of polymorphisms is the single nucleotide

polymorphism, which is a change in a single base pair (bp) in the genomic DNA. Single nucleotide polymorphisms can affect gene function. For example, a single nucleotide polymorphism located in a promoter region may influence the amount of mrna produced.

Another class of polymorphism is the simple sequence repeats, of which the common forms are the dinucleotide and trinucleotide repeats.

Page 19: Genetic polymorphism

• The variable number of tandem repeats (VNTR) can also influence the function of a gene, but the repeats are more likely to be linked with a functional polymorphism elsewhere in the gene.

• Another category of gene polymorphism involves insertions or deletions. Insertions and deletions can be as small as 1 base, in which case they may also be classified in the category of single nucleotide polymorphisms, but can also consist of a few bases, one or more exons, or even a whole gene.

Page 20: Genetic polymorphism

• Interleukin-1 gene polymorphism• Interleukin-2 gene polymorphism• Interleukin-4 gene polymorphism• Interleukin-6 gene polymorphism• Interleukin-10 gene polymorphism• Interleukin-12 gene polymorphism• Interleukin-18 gene polymorphism• Tgf-β gene polymorphism• Fc receptor polymorphism• Tnf-α• Human leukocyte antigen polymorphism• CD14 gene polymorphism• Toll like receptor gene polymorphism

• CARD15/NOD2 gene polymorphism• N-formyl-l-methionyl-l-leucyl-l-phenylalanine

receptor polymorphism• MMP polymorphism• Cathepsin C polymorphisms• Vitamin D receptor polymorphism• Calcitonin gene polymorphism• RANK/osteoprotegerin gene polymorphism• Plasminogen activator gene polymorphism

Page 21: Genetic polymorphism

• Nat2(n-acetyltransferase) gene polymorphism• Fibrinogen gene polymorphism• Estrogen receptor-α gene polymorphism• Cytochrome P450 gene polymorphism• Rage(receptor of advanced glycation end products) gene polymorphism• Ccr5(crotonyl coenzyme reductase 5) gene polymorphism• Lactoferrin gene polymorphism• Interferon-γ gene polymorphism.

Page 22: Genetic polymorphism

POLYMORPHISM IN RELATION TO PERIODONTAL DISEASES

Cytokine gene polymorphisms• IL-1 gene polymorphism • Tnf-a gene polymorphism • IL-10 gene polymorphism

Receptor and other gene polymorphisms I. Fcγr gene polymorphisms • FcγrIIa-131 H/R polymorphism • FcγrIIIa-158 F/V polymorphism • FcγrIIIb polymorphismI. Cytokine and chemokine receptor

gene polymorphisms II. Immune receptor gene polymorphism • FMLP receptor gene polymorphism

Page 23: Genetic polymorphism

Metabolism – related gene polymorphism • Vitamin D receptor gene polymorphism • Calcitonin receptor gene polymorphism Antigen – recognition related gene polymorphism • HLA gene polymorphism

Polymorphisms in the innate immunity receptors • TLR2 and TLR4 gene polymorphisms • CD 14 gene polymorphism • CARD 15 gene polymorphism Miscellaneous gene polymorphisms

Page 24: Genetic polymorphism

IL-1 GENE POLYMORPHISM

• Interleukin 1 is a multifunctional cytokine affecting most cell types with potent inflammatory and stimulatory properties.

• The il-1b gene located on chromosome 2 juxtaposed to the genes which encode the other cytokines of the il-1 family and their receptors (nicklin et al.1994). A cluster of genes regulating the production of these cytokines has been identified on the long arm of chromosome 2. (2q13). This cluster consists of the IL-1A, IL-1B and the Il-ra (receptor antagonist) genes.

Page 25: Genetic polymorphism

• In 1997, kornman et al found an association between polymorphisms in the genes encoding for il-1α and il-1β and an increased severity of periodontitis in caucasians.

• He reported 29.1% of northern european caucasian population evaluated as being genotype positive.

• In this study it was shown that individuals who carry a composite genotype (allele 2 of the il-1a polymorphism plus allele 2 of the il-1b polymorphism) are associated with a more severe periodontitis

• Genotype positive subjects have been described as presenting more rapid periodontal breakdown, increased bleeding on probing and an increased production of IL-1 by monocytes to the same bacterial challenge

Page 26: Genetic polymorphism

PERIODONTAL SUSCEPTIBILITY TEST [PST]

• IT IS MODIFIED TO ASSESS IL-1A +4845 & IL-1B +3954.• STEPS INCLUDE:-• Blood collection• Genotyping • Amplification and• Cycling.

Page 27: Genetic polymorphism

Page 28: Genetic polymorphism

Meisel et al 2002

Chronic 154 subjects caucasian Smokers and non smokers

Significant

Quappe et al 2004

Aggressive 36 patients with AgP, 75 healthy controls, and 75 subjects of unknown periodontal status

chile Smokers and non smokers

Significant

Meisel et al 2004

Chronic Randomly selected population based study

caucasian Smokers and non smokers

significant

Lopez et al 2005

chronic 330 patients with periodontitis and 101 healthy controls

Chile Smokers and non smokers

Significant

Wagner et al 2007

Chronic 194 individuals caucasian Non smokers Significant

Ferreira et al 2008

chronic 292 individuals Brazilian Non smokers Significant

Bernadette et al 2012 Chronic 49 with moderate 79 with severe chronic, 78 with aggressive periodontits

Mixed Non smokers Significant

Sasha et al 2013 55 individuals whites smokers significant

Page 29: Genetic polymorphism

INTERLEUKIN-10 (IL-10) POLYMPRPHISM

• The biological activities of IL-10 comprise suppression of pro-inflammatory cytokines produced by Th-1 cells (IL-2, ifn-g, TNF).

• The promoter region of the IL10 gene exhibits high frequencies of single nucleotide polymorphisms (snp) and microsatellites. There are three single-nucleotide polymorphisms (snps) in the IL10 gene at positions – 1087, –819 and –592 from the transcriptional start site which have been associated with altered synthesis of IL10 in response to inflammatory stimuli (turner et al. 1997).

Page 30: Genetic polymorphism

• The –1087 SNP Is A G To A Substitution And Lies Within A Putative Ets Transcription Factor Binding Site. The –1087G Allele Is Known To Be Associated With High In Vitro IL10 Production.

• The –819 Snp Presents A Dimorphic Polymorphism, A C To T Substitution, And May Affect An Estrogen Responsive Element.

• The –592 Snp Is A C To A Substitution And Lies Within A Region With A Negative Regulatory Function.

• It may therefore be anticipated that • (i) A homozygous GG –1087 genotype indicates considerably enhanced IL-10

production, • (ii) A heterozygous AG genotype moderate production and,• (Iii) A homozygous AA genotype reveals suppressed IL-10 production.

Page 31: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association

Trevilato et al 2003

  36 healthy individuals 24 with moderate and 24 with severe periodontitis

Brazil Nonsmoking

Significant

Komatsu et al 2005

chronic 112 subjects with CP and 77 healthy subjects

japanese Non smokers

Significant

Galicia et al 2006

Aggressive and Chronic

422 subjects 169nwith CP, 70 healthy, 43 AgP, 140 healthy

Japanese Non smokers

significant

Tervonen et al 2007

Chronic 51 subjects with moderate to severe CP and 178 reference group

Caucasian Smokers and non smokers

Significant

Guan et al 2008 Chronic 93 patients with periodontitis and 96 controls

chinese Smokers and non smokers

Significant

Nibali et al 2009 Aggressive and chronic

765 subjects Mixed Smokers and non smokers

Significant

Qianfu zhong et al 2012 Aggressive and chronic

1438 patients and 1303 control

Caucasians Non smokers Significant

Page 32: Genetic polymorphism

TNF- Α GENE POLYMORPHISM• TNF- α gene lies on chromosome 6 within MHC gene cluster. Gene

polymorphisms are G to A transition.• Chronic inflammatory bone diseases, such as rheumatoid arthritis,

periodontal disease, and aseptic periprosthetic osteolysis, are characterized by bone loss around affected joints and teeth caused by increased osteoclastic bone resorption.

• This resorption is mediated largely by the increased local production of proinflammatory cytokines, such as Tnf- α. Boyce et al 2005

Polymorphisms in the promoter region of the TNF- α gene at positions -238(G to A) and -308(G to A) have been reported• A lack of association between TNF- α polymorphism and periodontitis has

been consistently reported. Craandijk et al 2002; folwanczny et al 2004; Maria de freitas et al 2007.

Page 33: Genetic polymorphism

• Meta-analysis by nikolopoulos et al(2008) investigated the possible differential risk for periodontal disease of the tnf- α -308g/a allele. Study states the lack of association between the TNF- α-308g/A polymorphism and the susceptibility to CP.

Page 34: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association Craandijk et al 2002

Chronic 90 patients with periodontitis and 264 control reference subjects

Caucasian and non Caucasian population

Smokers and non smokers

Non significant

Soga et al 2003 Severe chronic 64 patients with severe adult periodontitis and 64 healthy subjects

Japanese Non smokers Significant

Shimada et al 2004

Chronic 58 patients with severe chronic periodontitis, 72 with moderate chronic, 52 controls

Japanese Non smokers significant

Babel et al 2006 Chronic 122 patients with chronic periodontitis and 114 controls

Caucasian Smokers and non smokers

Non significant

Maria de frietas et al 2007

Aggressive 30 patients with G-AgP periodontitis and 70 healthy

Brazilian Non smokers Non significant

Guzeldemir et al 2008

Aggressive 31 patients with L-AgP and 31 healthy controls

Turkish Non smokers Non significant

Wenwei yang et al 2013 Chronic and aggressive CP180, AgP 180 and healthy controls180.

chinese Non smokers significant

Page 35: Genetic polymorphism

FCΓR GENE POLYMORPHISMS

• Leukocyte IgG receptors(fcγr) serve as a link between the humoral and cellular branches of the immune system. Binding of the constant region of IgG to fcγr induces a plethora of cell type-specific pro and counterinflammatory functions. Fcγr polymorphisms influence the efficacy of cellular responses, and have been associated with inflammatory disease and disease severity

• Leukocyte fcγr belong to the ig superfamily. Divided into three classes, fcγri(cd64), fcγrii(cd32), and fcγriii(cd16), encompassing atleast 12 isoforms. Fcγr classes contain structurally and biochemically distinct molecules, and differ in cell distribution and affinity for igg subclasses.

Page 36: Genetic polymorphism

FCGRII POLYMORPHISM• A G to A transition polymorphism in the fcgrIIa gene results in the

substitution of histidine (H) for arginine (R) at amino acid position 131 of the receptor. FcgrIIa-h131 binds igG2 immune complexes efficiently, whereas the fcgriia-r131 allotype cannot mediate this interaction. Due to efficient binding of igg2 to neutrophils of the H/H131 genotype, these neutrophils may become hyperreactive. Possibly over activated neutrophils release more tissue-destructing molecules (such as lysosomal enzymes or matrix metalloproteinases) than less efficiently activated neutrophils (i.E. Cells with the fcgriia-r1 genotype).

• This polymorphism has been associated with EOP and with phagocytic function of neutrophils in conjunction with more severe periodontitis in adults (wilson & kalmar 1996)

Page 37: Genetic polymorphism

FCGRIII POLYMORPHISM

• The G to T transition polymorphism in the fcgriiia gene results in an amino acid 158-valine (V) substitution for 158-phenylalanine (F). The fcgriiia-v158 has a higher affinity for igg1 and igg3 than fcgriiia-f158.

• Subjects bearing the fcgriiia-v1 genotype, monocytes may produce higher levels of (pro-)inflammatory cytokines or chemokines than monocytic cells of f/f158 genotypes, and consequently mediate increased inflammatory activity and periodontal tissue destruction

• Kobayashi et al. 1997 reported a positive correlation between the fcgriiib-na2 allotype and recurrence of adult periodontitis

Page 38: Genetic polymorphism

• The study by loos in 2003 in northern european caucasians reported that(1) the fcgriiia-v158 allele was over represented in the patient group and therefore may be regarded as a putative susceptibility factor for periodontitis. (2) the fcgriia-h/h131 genotype was associated with more periodontal bone loss than the r1 genotype, indicative that the h/h131 genotype can be regarded as a putative severity factor for periodontitis.(3) the fcgriiia-v1 genotype was not identified as a severity factor. (4) the fcgriiib-na21 genotype was neither a susceptibility factor nor a severity factor.

Page 39: Genetic polymorphism

References Receptor Periodontitis Subjects Ethnicity Smoking Association Fu et al 2002 FCγRIIa

FCγRIIIaAggressive 48 patients with

L-AgP, 67 healthy controls

African-American population

  Significant

Loos et al 2003 FCγRIIaFCγRIIIaFCγRIIIb

Aggressive 12 subjects with AP, 56 with CP, 61 controls

Caucasian Smokers and non smokers

Significant

Yamamoto et al 2004

FCγRIIa Chronic 213 subjects with CP and 209 controls

Caucasian Smokers and non smokers

significant

De souza and Colombo 2006

FCγRIIaFCγRIIIb

Aggressive 31 patients with G-AgP and 49 healthy controls

Brazilian Nonsmokers Significant

Kobayashi et al 2007

FCγRIIaFCγRIIIaFCγRIIIb

Chronic 100 rheumatoid arthritis, 100 periodontitis, 100 healthy controls

Japanese Smokers and non smokers

Non significant

An et al 2009   Chronic and aggressive

30 AP, 131 CP, and 47 healthy patients

Chinese   Significant for aggressive non significant for chronic

Y wang et al 2012 Severe chronic 13 patients with periodontitis, 106 healthy patients

japanese Non smokers Significant

Page 40: Genetic polymorphism

FMLP RECEPTOR POLYMORPHISMS

• Human neutrophils play a key role in host defense against bacterial infections. Neutrophils are activated by the bacterial formyl peptide N- formyl-methionyl leucyl phenylalanine.

• It binds to specific formyl peptide receptor. These receptors are seven transmembrane pertussis toxin-sensitive G protein-coupled recptors.

• Ligand binding to fpr activates a number of downstream effector enzymes including phospholipase c, catalyzing the cleavage of phospotidylinositol 4,5-bisphosponate into secondary messengers inositol 1,4,5-triphosphate and diacylglycerol leading to calcium mobilization and activation of protein kinase c.

• Abnormal chemotaxis towards FMLP in lagp has been correlated with altered FPR activity.

Page 41: Genetic polymorphism

• In 1999 gwinn et al discovered occurrence of two polymorphism in the FPR gene of lagp patients, the third transmembrane helix of FPR 110 phenylalanine- serie (F110S) or 126 custient- trytophan (126W), suggesting a molecular alteration in this region may contribute to abnormal chemotaxis in lagp patients.

• Gwinn et al noted that the f 110s mutation was much more common among F110s lagp patients than c126w.

Page 42: Genetic polymorphism

VDR GENE POLYMORPHISM (VITAMIN D RECEPTOR GENE)

• Human VDR gene is localized in chromosome 12.• Mutations in functionally critical areas of vdr gene can have profound effect

on mineral metabolism and bone mineral density (bmd).• Vdr exerts its genomic action via the nuclear family receptor (vdr), which

shows an extensive polymorphism.• The vdr is an intracellular hormone receptor that specifically binds the active

form of vit d and interacts with target cell nuclei to produce a variety of biologic effects Yamada et al 2003.

Page 43: Genetic polymorphism

• A silent mutation with in the codon 352 of the ninth exon alters a Taq1 site. Hennings 1977 showed a significant relationship between Taq1 VDR gene polymorphism and EOP in caucasians

• The Tt gene might be a risk indicator for the susceptibility of EOP

Page 44: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association Inagaki et al 2003

Chronic 125 medically healthy middle aged men

Caucasian Smokers and non smokers

Significant

De brito Jr et al 2004

Chronic 44 healthy individuals and 69 subjects with CP

Mixed Non smokers

Significant

De souza et al 2007

Chronic 222 subjects with and without end stage renal disease were divided into with and without periodontitis

Brazilian   Non significant

Wang et al 2009

Chronic 107 patients with severe chronic periodontitis and 121 control subjects

Chinese Non smokers

significant

Hui deng et al 2011 Chronic and aggressive 1338 patients and 1302 controls

Mixed Smokers and non smokers

significant

Gurumoorthy karthikeyan et al 2013

Chronic 60 CP 60 healthy Dravidian Significant

Page 45: Genetic polymorphism

CALCITONIN GENE POLYMORPHISM

• Calcitonin is a hormone produced in the thyroid that causes a reduction of calcium ions in the blood.

• Suzuki et al 2004 investigated genomic markers for periodontitis, genomic DNA was obtained from 19 healthy volunteers and 22 patients with severe periodontitis, all of whom were japanese. Statistically significant differences were found between healthy and periodontitis patients in calcitonin receptor

Page 46: Genetic polymorphism

HUMAN LEUKOCYTE ANTIGEN• Human leukocyte antigen also called MHC, are involved in predetermined

humoral immune response via recognition of foreign antigens. • The HLA complex plays an important role in immune responsiveness and

may be involved in antigen recognition of periodontal pathogens. • In human, the classical mhc class i molecules(hla-a,b,c) are expressed on

most nucleated cells, while mhc class ii molecules(hla-dp,-dq,-dr) are expressed on cells that immunosurvey host cells including b and t cells, macrophages (takashiba 2006)

• Evidence for association of DR4 HLA and periodontal disturbance has been reported by (katz et al 1987). The HLA genotype HLA –DQBI * 0602 induced proliferation of T cells as an immune response against periodontal bacteria, P.Gingivalis. HLA –DRB1 *1501 was found to be responsible for this T cell proliferation. This accelerated T cell response led to increased susceptibility to EOP.

Page 47: Genetic polymorphism

• Meta-analysis performed by stein et al 2008 in caucasian population showed no significant HLA associations in patients with chronic periodontitis. Patients with aggressive periodontitis showed a positive relation with HLA-A9 and HLA-B15 as well as negative association with HLA-A2 and –B5.

• No significant associations were found with class II antigens stein et al. 2008.

Page 48: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association Machulla et al 2002

Chronic and aggressive

50 unrelated german Caucasian patients with RPP and a group of 102 unrelated german Caucasian patients with adult periodontitis are compared with a group of 102 healthy controls

Caucasian   Significant

Stein et al 2003 Chronic and aggressive

50 patients with generalized aggressive and 102 with CP, 102 healthy controls

Caucasian Smokers and non smokers

significant

Roshna et al 2006 Aggressive 40 patients with G-AgP and 80 controls

Indian population Smokers and non smokers

Significant

Reichert et al 2007

Chronic and aggressive

110 patients with juvenile idiopathic arthritis, 50 patients with G-AgP and 102 with CP, 102 with healthy

Caucasian Smokers and non smokers

significant

Page 49: Genetic polymorphism

TOLL LIKE RECEPTOR, TLR2 AND TLR4 GENE POLYMORPHISMS

• Toll was 1st discovered as drosophila gene. The gene product is a transmembranous protein, functioning as a signal transduction receptor.

• There are 10 TLRs, named tlrs1-10 known in mammals, and each of these receptors recognizes molecules derived from a unique class of microbial agents.

• Four adapter molecules are known to be involved in signaling.• These proteins are known as myd88, tirap, trif, tram. • These adapters activate other molecules in the cell, including protein kinases

that amplify the signal and lead to the induction or suppression of the genes that orchestrate the inflammatory response.

• All TLRs leads to activation of nfkb which produces proinflammatory cytokines, such as tnf-α, il-1 and il-2, there by regulating their expression.

Page 50: Genetic polymorphism

• Schroder et al 2005 reported that TLR-4 SNP were correlated with CP, but not with aggressive periodontitis.

• In a japanese population case control study, fukusaki et al 2007 revealed that the frequency of the c/c genotype in TLR4 3725G>C polymorphism was significantly higher in both the moderate and the severe periodontitis patient group than in the control group.

Page 51: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association D aluto et al 2004

Chronic 94 subjects with severe generalized periodontitis

Mixed Smokers and non smokers

Non significant

Laine et al 2005 Chronic 100 patients with severe periodontitis and 99 healthy controls

Caucasian Smokers and non smokers

Non significant

Berdeli et al 2007

Chronic 83 patients with CP and 106 periodontally healthy subjects

Caucasian Smokers and non smokers

Non significant

Imamura et al 2008

Chronic 43 patients with periodontitis and 49 healthy controls

Japanese   Non significant

Page 52: Genetic polymorphism

CD 14 GENE POLYMORPHISM

• The CD14 receptor is a glycoprotein that is expressed primarily on the surface of monocytes ,macrophages,neutrophils and gingival fibroblasts and is involved in the process of cellular response to bacterial LPS.

• The cd14 protein is expressed in two phenotypic forms .M cd 14 and sCD 14. • Scd14 is present in the serum. • LPS induced upregulation of sCD14 seems to elicit an increased production of il-

2 by apc (antigen presenting cells). • Systemic level of soluble cd14 increases in periodontal disturbances.

Page 53: Genetic polymorphism

• CD14 gene exists as a single copy gene. • This polymorphism comprises a C to T substitution to position -159 to the

5’flanking region of the CD 14 gene.• It has been demonstrated that C to T transformation at position -159 is

related to the production of s cd14. • Frequency of c allele carriage tends to be larger in subjects with severe

periodontitis.• The systemic level of the soluble form of cd14(scd14) is significantly

increased in patients with periodontal disease(hayashi et al 1999)• CD14 expression within the periodontal tissue was found to be negatively

correlated with the amount of attachment loss(jin 2001).• Reduced expression of cd14 on monocytes was suggested to an increasing

susceptibility for EOP (buduneli et al 2001).

Page 54: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association Yamazaki et al 2003

Chronic 163 subjects with periodontitis and in 104 healthy controls

Japanese Non smokers

Non significant

Laine et al 2005

Chronic 100 patients with severe periodontitis and 99 controls

Caucasian Smokers and non smokers

Significant

James et al 2007

Chronic and aggressive

73 subjects with AP, 95 subjects with CP, 95 healthy controls

Caucasian Smokers and non smokers

Non significant

Donati et al 2008

Chronic 53 subjects with generalized and severe periodontitis

Caucasian Smokers and non smokers

Non significant

Page 55: Genetic polymorphism

CARD15/NOD2 GENE POLYMORPHISM•Nucleotide-binding oligomerization domain receptors, including NOD1, NOD2, and ICE protease activating factor(ipaf), are cytoplasmic receptors for recognition of microbial products.

•These receptors detect organisms that enter the cytoplasm of the cell, or products that may be released or transported into the cytoplasm by processes such as phagocytosis and degradation of microbes.

•Nod1 and Nod2 interact with receptor interacting protein 2(RIP2), also called RICK, a protein consisting of a kinase domain and a CARD.

Page 56: Genetic polymorphism

• RIP2 directly interacts with inhibitor of NFkB kinase γ (IKK γ), leading to ubiquitinylation of IKKγ and activation of the kinase activities of ikkα and ikkβ, this results in the activation of the proinflammatory responses mediated by nfkb (ferrero et al 2007)

• A clear mrna expression of NOD1 and NOD2 was revealed in gingival fibroblasts(uehera et al 2007) and in oral epithelial cells(sugawara et al 2006).

Page 57: Genetic polymorphism

References Periodontitis Subjects Ethnicity Smoking Association Laine et al 2004

Chronic 104 dutch Caucasians with severe adult periodontitis and in 97 healthy controls

Caucasian Smokers and non smokers

Non significant

Noack et al 2006

Aggressive 86 generaized aggressive periodontitis patients I comparison with 67 healthy controls

Caucasian Smokers and non smokers

Non significant

Page 58: Genetic polymorphism

MISCELLANEOUS GENE POLYMORPHISMSINTERLEUKIN-2 (IL-2) GENE POLYMORPHISM • IL-2 is a proinflammatory cytokine derived from Th1 cells.• Il-2 is involved in b-cell activation and stimulates macrophages, nk cells, t cell

proliferation, and osteoclast activity.• A polymorphism in the position -330 (T-G) of the il-2 gene promoter was

identified by john et al. (1998). This polymorphism could be useful as a marker to diagnose susceptibility to inflammatory diseases.

Page 59: Genetic polymorphism

INTERLEUKIN-6 (IL-6) GENE POLYMORPHISM• Interleukin-6 (IL-6) plays a role in B cell differentiation and t-cell proliferation. It also stimulates

hematopoiesis and accelerates bone resorption. • High levels of il-6 in biological fluids and blood have been determined in chronic inflammatory

diseases. Higher levels of il-6 were found in sites with gingivitis when compared to healthy sites.

• Polymorphism occurs due to transition of G to C at position 174 in the promoter region of IL6 gene

• The C allele was shown to alter the IL-6 gene transcription response to stimuli such as LPS and IL-1.

• Trevilatto 2003 first reported that the genotype g/g of the il-6_174 polymorphism was significantly associated with susceptibility to chronic periodontal disease

Page 60: Genetic polymorphism

MMP POLYMORPHISMS

• The degradation of periodontal tissues is mainly mediated by matrix metalloproteinases (MMPs).

• Many types of MMPs have been identified in inflamed periodontal tissues and these enzymes are thought to play an important role in tissue destruction in periodontal diseases (birkedal-hansen 1993).

Page 61: Genetic polymorphism

MMP-1 PROMOTER POLYMORPHISM

• Fibroblast type collagenase (MMP-1) is the major type of proteolytic enzyme that can cleave native interstitial collagens type I and III, which are the most abundant protein components of periodontal extracellular matrix.

• Matrix metalloproteinase-1 seems to play an important role during the destruction of the extracellular matrix in periodontal disease.

• The MMP-1 gene is located in 11q22 and is translated in a wide variety of cells, e.G. Fibroblasts, macrophages, endothelial, and epithelial cells.

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• The level of MMP-1 expression can be influenced by the polymorphism in the promoter region of the MMP-1 gene resulting from a guanine insertion at –1607 bp (i.E., The GG versus G variants), which results in the creation of a binding site for the ets family of transcription factors as well as in the increased transcription of the MMP-1 gene and increased enzyme activity polymorphism in the promoter region of human MMP-1 gene has been described

• The two alleles (1G and 2G) are formed by an insertion/deletion of a guanine at position ª1607

• Izakovic¡ova 2004 reported that the polymorphisms in the MMP-1 promoter may have only a small effect on the etiopathogenesis of chronic periodontitis.

• Astolfi 2006 investigated the relationship between polymorphisms in mmp-1 (-1607 1g/2g, -519 a/g) with chronic periodontitis in a brazilian population. And showed that no significant association is found for the MMP-1 polymorphisms with susceptibility of periodontitis.

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MMP-3 PROMOTER GENE POLYMORPHISM

• Astolfi 2006 studied MMP-3 (-1612 5A/6A) gene promoter polymorphisms using PCR-RFLP methods and showed that the 5A/5A genotype was significantly more frequent in the periodontitis group and reported that MMP-3 gene polymorphism may contribute to periodontal tissue destruction during periodontitis in brazilian subjects.

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MMP-9 PROMOTER GENE POLYMORPHISM

• Keles JC 2006 investigated the association between MMP-9 promoter polymorphism and severe generalized chronic periodontitis in a turkish population.

• The alleles of the C/T polymorphism at position -1562 in the promoter region of the MMP-9 gene showed a significant difference in MMP-9 genotypes between chronic periodontitis patients and healthy controls suggesting that MMP-9 promoter gene polymorphism seems to be associated with severe generalized chronic periodontitis.

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RAGE GENE POLYMORPHISM AND PERIODONTITIS

• RAGE (receptor for advanced glycation end products) is a multiligent member of the ig super family of cell surface molecules, initially identified as a cellular interaction site for AGEs. RAGE gene is localized to the sixth chromosome region. Polymorphism of RAGE gene may contribute to individual’s susceptibility to develop chronic periodontitis, independently of diabetes .

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PROVING A DISEASE/POLYMORPHISM RELATIONSHIP

• POLYMORPHISM MUST INFLUENCE THE GENE PRODUCT.• BIASES IN THE STUDY POPULATION SHOULD BE RECOGNIZED AND

CONTROLLED.• AFFECTED GENE PRODUCT SHOULD BE THE PART OF DISEASE ETIO-

PATHOLOGY.• CONFOUNDERS SUCH AS SMOKING AND SOCIOECONOMIC CLASS MUST BE

CONTROLLED.

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CLINICAL UTILITY OF GENETIC KNOWLEDGEPolymorphisms associated with periodontitis illustrate a number of important points with respect to the clinical interpretation of this type of information.• The associations between particular genes and disease may only (thus far)

be apparent in certain populations and not in others. Thus, genetic tests based upon these genes may not apply to all patients.

• The associations between groups of interacting genes and disease may be stronger than those between individual genes and disease. Therefore, as more genetic risk factors are found, genetic tests for disease risk will continually evolve and merit scrutiny and evaluation.

• The associations between disease and genes may be indirect, that is, genetic factors may be associated with environmental risk factors for periodontitis (e.g. Smoking) and thereby influence disease only in those patients with the relevant biological exposure.

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GENETIC SCREENING FOR PERIODONTITIS RISK

• The current practical clinical utility of genetic knowledge in periodontics is limited. However, performing clinical periodontal assessments of siblings of AgP probands is one of the most useful actions we can perform to ensure the early diagnosis of this disease.

• By careful clinical diagnostic procedures, we may detect susceptible patients early and instigate therapy, which may prevent the more significant disease aspects from occurring. In the pursuit of better genetic diagnostic tests for chronic and aggressive periodontitis, we must plan our research using plausible biological arguments and carefully avoid bias and misinterpretation of genetic associations with disease.

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FUTURE APPLICATION OF GENETIC INFORMATION

PROGNOSTIC TESTS:• Genetic tests, should predict the likelihood of disease initiation before it

occurs and ultimately will be linked to knowledge of the environmental factors that can initiate the inappropriate activation of genes that are problematic.

• Knowledge of the genetic profiles of individuals who are susceptible to periodontitis will identify those individuals whose environmental exposures must be modified in order to prevent disease.

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DIAGNOSTIC TESTS• A great deal of research has been performed in an attempt to detect active

disease or subclinical initiation of disease but no universally accepted test has emerged for clinical application.

• Prognosis and diagnosis can become tightly linked because both a genetic profile would be available and a gene-expression profile could be monitored over time.

• Once the genetic risk and specific genetic risk factors for a given patient are known, tests of gene activation might be individually targeted and test intervals could be tailored to the susceptible patient.

• The specific environmental exposures leading to gene activation may be more clearly known.

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CONCLUSION

• Periodontitis is clearly multifactorial and researchers need to design studies that examine the role of important environmental and genetic factors simultaneously.

• Given the large number of genes in the human genome and bacteria in the oral cavity, it is likely that genes and the environment interact in important yet unrecognized ways to alter disease risk. Identifying specific genetic risk factors may be academically appealing but is of little use unless it leads to improvements in the prevention/treatment of disease.

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REFERENCES

• Clinical text book of periodontology, newmann, takei, carranza. 10th edition, pg no:193-206.• Clinical periodontology and implant dentstry, 5th edition, jan lindhe. Pg no:329-340.• Fundamentals of periodontics, thomas g wilson, 2nd edition, pg no:171-182.• Periodontal medicine and systems biology, brian hinderson.• Periodontics, b meley, 5th edition, pg no 49-50.• Modifying disease genes in relation to periodontics.• Genetic polymorphisms in periodontal disease: an overview, r vijayalakshmi et al, indian journal

of dental research, 21(4), 2010.• Gene polymorphisms and periodontitis, jingai zhang et al, periodontology 2000, vol 56, 2011,

102-124.• The role of genetic polymorphisms in periodontitis, hiromasha yoshie et al, periodontology 2000,

vol 43, 2007, 102-132.

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• Determinants of host susceptibility in aggressive periodontitis, huanxin meng, periodontology

2000, vol 43, 2007, 133-159.• Genetic polymorphism studies in periodontitis and fcγ receptors, jperiodontal research 2012, 47,

273-285.• Influence of mmp8 promoter polymorphism in early osseointegrated implant failure, f.R costa et

al, clinical oral investigation 2013, 17:311-316.• Association of il8 gene polymorphism with clinical parameeters and chronic periodontitis,

hengameh khosropanah et al, journal of dentistry 2013, vol10,no4.• Association between il6 polymorphisms and periodontitis in indian non smokers.• Mendelian form of periodontitis, thomas c. Hart et al, periodontology 2000, vol 45, 2007, 95-112.• The association of fcγ receptor iiib genetic polymorphism and susceptibility to periodontitis in

taiwanese individuals, ho y-p et al, journal of clinical periodontology 2010, 37: 145-151.• Association of toll like receptor 9 haplotypes with chronic periodontitis in czech population. Holla

li et al, JCP 2010, 37: 152-159.• A comparative study of th role of cytokine polymorphisms il10 and tnfα in susceptibility to

implant failure and chronic periodontitis. Ceyda gurol et al. The international journal of oral and maxillofacial implants 2011, 26:955-960.

• Genetic polymorphism of fcγ receptors iia, iiia and iiib in south indian patients with generalized aggressive periodontitis, journal of oral science, vol 53, no4, 467-474.