Periodontitis is an
inflammatory disease affecting the supporting tissue of teeth. Chronic
periodontitis is the most prevalent form of periodontitis. “Chronic
periodontitis is defined as an infectious disease resulting in inflammation
within supporting tissues of teeth, progressive attachment and bone loss”. A
number of different factors influence the etiopathology of chronic
periodontitis. Periodontal disease is a multifactorial disease that includes, Microbial
factors within the presence of microbial biofilm, local factors within plaque
accumulation and development of biofilm.1
Genetic factors includes
variation in genetics, single nucleotide polymorphism (SNPs) and genetic copy
number variation. SNPs is a variation in the single nucleotide that occurs at
specific position in the genome.Single nucleotide polymorphism occurs in the
coding region and in non coding region. Single nucleotide occuring in the
coding region may be synonymous (not affecting protein sequence) or non
synonymous (change in protein sequence).
SNPs may affect susceptibility of human being to various disease.
Genetic copy number
variation (CNVS) in sections of genome that are repeated. This
genetic variation can involve
differences in the DNA nucleotide sequence as well as changes in chromosome
structure. Single nucleotide polymorphisms (SNPs) are common variants of
individual nucleotide sequence that are frequently observed in the population (>1%).
CNVs are a type of structural variant involving alterations in the number of copies
of specific regions of DNA, which can either be deleted or duplicated.2 Genetic
variation in the human genome takes many forms, ranging from large microscopically-visible
chromosome anomalies to single nucleotide changes.
studies have discovered an abundance of sub-microscopic copy number variation
of DNA segments ranging from kilobases (kb) to megabases (Mb) in size 1-8.
Deletions, insertions, duplications, and complex multi-site variants 9, collectively
termed copy number variants (CNVs) or copy number polymorphisms (CNPs), are
found in all humans 10 and other mammals examined.3 By various
molecular mechanisms, including gene dosage, gene disruption, gene fusion,
position effects, etc., CNVs can cause Mendelian or sporadic traits, or be
associated with complex diseases. However, CNV can also represent benign
polymorphic variants. CNVs, especially gene duplication and exon shuffling, can
be a predominant mechanism driving gene and genome evolution.4
Genetic CNVS and SNPs may
directly influence innate and acquired immune response as well as structure of
periodontal tissue. Studies of SNPs as IL-1 gene has been providing evidence
that alteration in sequence of immunologically related genes may explain the
heritability of periodontitis.1 The variants may have positive or
negative influence on the disease. Few variants may increase susceptibility to
disease and few variants may decrease susceptibility to disease.Within the
availablity of human genome sequence and the knowledge of the complement of
genes. It should be possible to identify
the metabolic pathways involved in periodontal destruction and regeneration.
Most term of periodontitis represents a life long accounts of interaction
between genome, behaviour and environment.
polymorphism refers to difference in expression of cytokine are of great interest in periodontal research. IL-1
SNP IL-1A -889 in promoter or IL-1B +3954 gene associated with severe
periodontitis. Other cytokine like IL-2 SNPs, IL-4 SNPs were associated with
aggressive periodontitis. IL-6 SNPs were associated with protection against
periodontitis in IL-10,IL-4,IL-6,IL-8,IL-18,TNF-? etc, gene polymorphism were
studied and found to have an effect on periodontitis.
polymorphism occurs in FC g receptor of Ig G are also associated with chronic periodontitis. Toll like receptor
(TLR) gene polymorphism especially in TLR4 gene polymorphism acts as a risk
factor for the development of chronic periodontitis. CD14 gene polymorphism,
polymorphism, RANKL polymorphism,
Vitamin D gene polymorphism have etiological role in chronic periodontitis.
Newer studies have revelled association of antigen-antibody polymorphism and
gene coding enzyme polymorphism like cathepsin C gene polymorphism,
MMP-1 promoter gene polymorphism etc with chronic and severe periodontitis.
My library dissertation
titled SINGLE NUCLEOTIDE POLYMORPHISM
(SNPs) IN CHRONIC PERIODONTITIS presents an overview of effect of SNPs in
periodontitis, with better understanding of effect of SNPs on periodontitis and
careful clinical diagnosis and its procedures, susceptible patients may be
detected early and therapy may be
investigated which helps to prevent more severe aspect of disease than
occurring and to start therapeutic intervention at right time.