Terminologies in Genetics Genetic study design genetic syndrome and disease associated with periodontal diseases, heretibility of periodontal disease, gene library, gene therapy

1. GENETICS IN
PERIODONTICS
PRESENTED BY:
ANUSHRI GUPTA
PG 2ND YEAR
Dept of Periodontology

2. CONTENTS
PART 1
• INTRODUCTION
• TERMINOLOGIES
• HUMAN GENOME PROJECT
• GENETICS & PERIODONTICS
• LEADING PERIODONTAL
CONCEPTS
• GENETIC TESTING
• GENES IN PERIODONTAL
DISEASES
• GENETIC STUDY DESIGNS
PART 2
• HERITABILITY
• PERIODONTITIS IN GENETIC
SYNDROMES & OTHER
DISEASES
• GENE LIBRARY
• GENE THERAPY
• CONCLUSION
• REFERENCES

3. INTRODUCTION
• Gingivitis and periodontitis are among the most common diseases known to man.
• Although bacterial plaque is generally accepted as the primary etiologic agent, little
information is available concerning the influence that host genetic factors have on
these diseases.
• The clinical severity of periodontal disease was evaluated in 110 sets of adult
identical (monozygous) and fraternal (dizygous) twins.
• It was determined that around 38-82% of the clinical severity of the disease was
explained by genetic factors.
(Michalowicz et.al 1991)

4. GENETICS
• Genetics is a branch of Biology concerned with the study
of genes, genetic and heredity in living organisms.
• “Gregor Johann Mendel” – “Father of Genetics”
• “Trait inheritance”

5. TERMINOLOGIES
GENE: The segment of the genome that carries the instructions for a specific
protein is the “Gene” for that protein.
GENOME: term used to refer all the genes carried by an individual or a cell.
GENETIC CODE: the consecutive nucleotide triplets that specify the sequence
of amino acids for protein synthesis.
LOCUS: the physical location of a gene
occupies within a chromosome or portion of
genomic DNA.
ALLELE: Alternative forms of a given gene differing
in DNA sequence.
• Alleles can be identical – homozygous
• Alleles can be different – heterozygous
• If only one allele is present – hemizygous

6. • GENOTYPE: genetic makeup of an organism or cell.
• PHENOTYPE: The expression of a genotype is termed a
phenotype. For example, hair color, weight, or the presence or
absence of a disease.
• LINKAGE: the tendency for certain genes to be inherited together
due to their presence on the same chromosome.
• POLYMORPHISM: When a mutation increases to a level involving
>1% of the population, it is referred to as polymorphism.
• The different types of polymorphisms are typically referred to by
the type of mutation that created them.
Single nucleotide polymorphism (SNP):
• The simplest type of polymorphism results from a single base
mutation which substitutes one nucleotide for another.

7. Restriction Fragment length polymorphism
(RFLP)
• Digestion of a piece of DNA, with an
appropriate restriction enzyme could then
distinguish alleles or variants based on the
resulting fragment sizes, via gel-
electrophoresis process.
Insertion-deletion polymorphism: (indel)
• Results from insertion or deletion of a section
of DNA.
• An indel in the coding region of a gene that is
not a multiple of 3 nucleotides results in a
frameshift mutation.

8. • It has been widely accepted that the
differences among individuals at risk for
developing most diseases have a
substantial inherited pattern.
• Most cases of periodontitis appear to fit
this complex genes and environmental
model.
• The inherited variation in DNA has a role
roughly equal to that of the environment
in determining who remains
periodontally healthy versus who is
affected by this disease.
ENVIRONMENTALFACTORS
(diet,smoking,preventive
care, exposure to
pathogens)
GENETIC FACTORS
INTERACT WITH EACH
OTHER TO DETERMINE
PERSON’S HEALTH
OUTCOMES.
Determines if and when the disease affects the person,
how fast and how severely symptoms of the disease
progress and how the person responds to different
treatments in terms of both side effects and success of
alternative therapies.

9. Human Genome
• Most human cells contain 46 chromosomes:
• 22 pairs of chromosomes named autosomes.
• 2 sex chromosomes (X,Y):
XY – in males.
XX – in females.
• Each maternal and paternal pair represent
homologous chromosomes - called homologs
Homologous Chromosomes
• Chromosome – double stranded DNA
molecule, packaged by histone & scaffold
proteins
• Share centromere position
• Contain identical gene sets at matching
positions (loci) for color or shape

10. Chromosome Structure

11. DNA Structure

12. Gene Expression
• Genes are made up of promoter regions and
alternating regions of introns (noncoding
sequences) and exons (coding sequences). The
production of a functional protein involves the
transcription of the gene from DNA into RNA,
the removal of introns and splicing together of
exons, the translation of the spliced RNA
sequences into a chain of amino acids, and the
posttranslational modification of the protein
molecule.
• CENTRAL DOGMA OF MOLECULAR BIOLOGY

13. • The Human Genome Project (HGP) was an international scientific research project
with the goal of determining the base pairs that make up human DNA, and of
identifying and mapping all of the genes of the human genome from both a physical
and a functional standpoint.
• 1984 by the US government,
• launched in 1990,
• complete on April 14, 2003

14. GOALS:
• Identify all the approximate 30,000 genes in human DNA.
• Determine the sequences of the 3 billion chemical base pairs that make up human DNA.
• Store this information in databases.
• Improve tools for data analysis.
• Transfer related technologies to the private sector, and
• Address the ethical, legal, and social issues (ELSI) that may arise from the project.

15. HGP CONCLUDED:
• The human genome is nearly the same (99.9%) in all people.
• Only about 2% of the human genome contains genes, which are the instructions for
making proteins.
• Humans have an estimated 30,000 genes; the functions of more than half of them
are unknown.
• Almost half of all human proteins share similarities with other organisms.
• About 75% of the human genome is “junk”.

16. Effective factors in periodontal disease. The effective factors of periodontal disease
include microbial factors, systemic disease, environmental factors, age, gender and
genetics. Allelic variants of genes can increase risk of periodontal disease.
GENETICS & PERIODONTITIS

17. • Some data suggests that Smoking, DM, and Genetic influences put certain
individuals at a high risk for severe periodontitis.

18. LEADING PERIODONTAL CONCEPTS
1965-1995:
• Three popular assumptions guided periodontal treatment:
i. Populations with poor plaque control and limited professional dental care
have widespread severe periodontitis.
ii. Individuals with poor plaque control for many years have severe generalized
periodontitis.
iii. The severity of the disease depends on the combination of the bacterial
challenge and the length of time of exposure to the bacteria.

19. Today:
i. Periodontitis require specific bacteria for the initiation and progression of
attachment loss and bone loss.
ii. There is “normal” host response to this bacterial challenge.
iii. Although the normal host response is primarily protective, it also causes tissue
destruction.
iv. Healing and repair are constantly going on process in the periodontal tissues.

20. V. In the majority of individuals with a moderate bacterial challenge, protection and
repair dominate destruction, and very little disease is clinically evident.
Vi. Some patients have “altered” host responses and develop more severe destruction.
Vii. Altered host responses may result from:
a) heavy bacterial challenges overwhelming the protective and repair mechanisms.
b) the presence of disease modifiers that reduce the protective component of the host
response or amplify the destructive component.

21. MODIFYING FACTORS:
• The factors that determine the severity and
response to treatment are often called
“Disease modifiers”.
• They change the trajectory of the clinical disease
expression over time.
• So, an individual with a disease modifier is at
increased risk for more severe signs and
symptoms at any given time in the disease, as
compared with an individual without that
modifier.
• Eg; Smoking , diabetes and IL-1 genetic
variations

22. Genetic epidemiology
• The field of research that unearth the complex interactions between genes and environment
that underlie individual differences in disease susceptibility.
• Populations adapt genetically to their local environment, NATURAL SELECTION (Differential
survival or reproduction)
Eg. Sickle cell hemoglobin variant protects against the infectious disease malaria. It is common in
areas where malaria borne parasite is an endemic because it provides strong protection
against this disease.

23. Genetic Drift
• Causes populations with little or no migration between them to differentiate genetically
over the time, so one cannot assume that every population difference observed has a
functional biological basis.
• Comparison of periodontitis in different populations across the globe is extremely
challenging because of the lack of calibrated examiners and standardized disease
definitions.

24. • Comparison of disease occurrence or severity in identical (monozygotic) versus nonidentical (dizygotic)
twins is a very powerful method for distinguishing between effects caused by variation in genes versus
factors in environment.
• If VARIATION among individuals in disease susceptibility or severity is caused entirely by FACTORS IN
ENVIRONMENT : pairs of identical twins are no more similar to each other than pairs of nonidentical
twins.
• If VARIATION among individuals in disease susceptibility or severity is caused entirely by GENETIC
FACTORS: genetically identical twin pairs will be more similar to each other than nonidentical twin
pairs.
• This is because identical twins share 100% of the same genes, whereas non identical twin pairs share
only 50% of their parent’s genes on average.

25. GENETIC TESTING
• Any cellular material including a blood sample or a scraping of cells from the
inside of the cheek, may be examined.
3 types:
A. Testing for chromosomal abnormalities such as “Trisomy 21”.
B. Testing for unusual mutations, such as BRCA1 as a risk factor for Breast
cancer.
C. Testing for common polymorphisms, such as those being studied for risk of
severe periodontal disease.

26. GENES ARE IMPORTANT FOR PERIODONTAL DISEASES:
a) IL-1
b) PGE2
c) TNF-α
d) Matrix Metalloproteinases (MMP’s).

27. • There are many reports associating IL-1 levels in tissues and GCF with bone loss in more
advanced or severe periodontitis.
• Recent studies comparing the severity of bone loss with IL-1 levels in GCF showed
essentially a Straight-line relationship i.e; “the higher the levels of IL-1 in crevicular
fluid, the more severe is the bone loss”.
• Other studies showed that specific blocking of IL-1 & TNF-α in the gingival tissues,
without any plaque control measures, blocked a substantial part of the bone loss in
periodontal disease.

28. • The extensive research of the past 20 years considers the following as
factors for genetic influences on periodontal disease differences among
individuals:
i) IL-1
ii) TNF-α
iii) PGE2
iv) Cytokines that regulate immuno-inflammatory processes- IL-10, IL-4, IL-13,
IL-12.
v) Growth factors involved in wound healing and bone metabolism such as
TGF, PDGF.

29. DETERMINING GENETIC VARIATIONS INVOLVED IN PERIODONTAL DISEASES:
A. Use of Candidate genes
B. Genomic scan
C. Proteomics

30. CANDIDATE GENES: Genes which are known to influence some key aspect of the biology
involved in the disease.
• Candidate genes in SNP’s are studied for association with disease.
GENOMIC SCAN: Starts with specific variations in the nucleotide sequence that are
located along the entire genome.
• The markers that are found to be associated with the disease define the physical
locations in the genome that are more likely than others to influence that disease.
• Each physical location that is identified on the genomic scan must then be explored
for potential genes of importance.
PROTEOMICS: involves the analysis of those genes that are more activated during the
disease.

31. GENETIC STUDY DESIGNS
a) Which alleles have measurable effect on phenotype,
b) Whether the prevention, diagnosis, or treatment of the disease can be improved,
once disease alleles are identified.
Study designs:
i) Family studies
ii) Twin studies
iii) Population studies

32. FAMILY STUDY:
• Inherited diseases “run” in families.
• Thus, it is important to consider the shared environmental and behavioral risk factors in
any family.
• These would include
 education,
 socio-economic grouping,
 oral hygiene,
 possible transmission of bacteria,
 diseases such as diabetes, and
 environmental features such as passive smoking, sanitation, etc.
(Kinane and Hart 2003).

33. • Some of these factors, such as lifestyle and behavior and education, may be
under genetic control and may influence the standard of oral hygiene.
• The complex interactions between genes and the environment must also be
considered in the evaluation of familial risk for the periodontal diseases

34. TWIN STUDIES:
• The relative influence of genetic and environmental factors on complex diseases can be
estimated using twin studies.
• These studies are based on the fact that dizygotic twins share on average 50% of the genes by
descent, while the genes in monozygotic twins are identical.
• Monozygous twins arise from a single fertilized ovum and are therefore genetically identical
and always the same sex.
• Dizygous twins arise from the fertilization of two separate ova and share, on average, one half
of their descendent genes in the same way as siblings do.

35. • Any discordance in disease between monozygous twins must be due to environmental factors.
• Any discordance between dizygous twins could arise from environmental and/or genetic
variance.
• Therefore, the difference in discordance between monozygous and dizygous twins is a measure of
the effects of the excess shared genes in monozygous twins, when the environmental influence is
constant.
(Hodge and Michalowicz 2001).
• Thus, if heredity plays a significant role in periodontitis, the probability of having the same disease
in monozygotic twins will be much higher than in dizygotic twins.

36. POPULATION STUDIES
• A genetic polymorphism is the long-term occurrence in a population of two or more
genotypes that could not be maintained by recurrent mutation.
• A significant difference in the frequency of a specific polymorphism, between a
diseased group and a control group, is an evidence that the candidate gene plays
some role in determining susceptibility to the disease.
• An association indicates that either the candidate gene directly affects disease
susceptibility or that it is in linkage disequilibrium with (very close to) the disease
locus.

37. • This method can help to elucidate:
 the pathogenesis of a disease process,
 identify causal heterogeneity, and
 ultimately identify individuals most at risk for the disease.
• In population studies, it is important to clearly define the disease status.
• Likewise, because of the possibility of racial heterogeneity, it is important to insure that
the patient and control groups are racially matched.
(Hodge and Michalowicz 2001).

38. STUDY DESIGNS FOR IDENTIFYING
THE DNA VARIANTS
LINKAGE ANALYSIS
• A technique used to map a gene responsible for a trait to a specific location
on a chromosome.
• These studies are based on the fact that genes that are located close to each
other (20-30 centimorgan) on the chromosomes tend to be inherited
together as a unit.
• These genes are said to be linked.

39. LIMITATION:
• Many diseases are caused by multiple genes (each contribute to a small amount to the
phenotype/disease/ trait).
• It has extremely low statistical power for complex diseases in which there is extensive
heterogeneity among different families that have different combinations of susceptibility genes
and environmental exposures.

40. ASSOCIATION ANALYSIS
• This analysis aims to identify which genes are associated with the disease.
• It includes candidate’s gene mapping approach that tests whether one allele of a gene occurs
more often in patients with the disease than in subjects without the disease.
• Candidate genes are chosen on the basis of their known or presumed function (i.e. they have
some plausible role in the disease process such as producing a protein that is important in
disease pathogenesis).

41. • These are sometimes referred to as case control studies .
• Genotype frequencies of an inherited DNA variant for a group of periodontitis cases
are statistically compared to periodontally healthy control subjects.
• If the genotype frequencies differ so greatly that the results are very unlikely to occur
by chance, it is concluded that the genotype that is more common in cases than
controls is associated with increased disease risk.

42. SEGREGATION ANALYSIS
• Statistical analysis of the patterns of transmission of a disease in families in an attempt to
determine the relative likelihood that the disease is caused by
 a single gene with dominant or
 recessive inheritance, by multiple genes or
 entirely by variation in exposure to risk factors.
• This is relatively straight forward for traits in which mutation in a single gene causes the
disease to develop with nearly 100% certainty in carriers, whereas persons who do not inherit
the mutation are at little or no risk.

43. • The pattern of inheritance through generations depends on
i) Autosomes / Allosomes
ii) Dominant / Recessive
iii) Fully or Partially Penetrant
• “Penetrance” refers to the probability that a particular phenotype will result from a genotype.
• “Partially penetrant” means that only a fraction of individuals who inherit the disease alleles
will be affected.
• Eg. Huntington’s disease is a single dominant gene disorder because it is transmitted with 50%
probability to offspring of affected individuals
LIMITATION:
• Generally segregation analysis cannot distinguish between genetic effects and measured
environmental causes of disease.

44. Combination of multiple genetic and environmental factors
make the challenge of deciphering genetic mechanisms by merely
observing transmission patterns in families using the
segregation analysis.
HIGHLY COMPLEX
DISEASES
High risk gene does
not automatically lead
to development of the
disease
(REDUCED
PENETRANCE)
Several genes or even
dozens of different
genes may influence
Disease Susceptibility
(GENETIC
HETEROGENEITY)
Environmental
exposures are also
Important modifiers
of disease risk.

45. PART 2
HERITABILITY
PERIODONTITIS IN GENETIC
SYNDROMES & OTHER DISEASES
GENE LIBRARY
GENE THERAPY
CONCLUSION
REFERENCES

46. HERITABILITY
• Heritability estimates the portion of all variations in the trait that is attributable to inherited
genetic variations.
• It is always specific to a particular population in particular surroundings.
• Traits whose variation is determined entirely by differences in environmental exposure have
heritability of 0.0.
• Traits with variation attributable solely to genetic differences have heritability of 1.0
• Most human diseases and non disease traits fall in the middle of this range between 0.25 and
0.75.

47. HERITABILITY OF GINGIVITIS
• It is feasible that genes implicated in the regulation of inflammatory process of periodontal tissues
associated with plaque accumulation may play a role in explaining the individual variability in the severity
of both plaque-induced gingivitis and destructive periodontitis
(Dashash et al. 2007)
• Periodontal disease development and progression can be caused by MMPs produced by both infiltrating
and resident cells of the periodontium.
• One of the most important MMPs, MMP-9 (also known as gelatinase B or 92-kD type IV collagenase), is
active against collagens and proteoglycans.
• The coding gene is located on chromosome 20 q11.2- q13.1, and several polymorphisms have been
detected in the MMP-9 gene
(Vokurka et al. 2009)

48. GENES ASSOCIATED WITH GINGIVITIS RISK:
• IL-1 cluster, IL-6,10, 12,18
• MMP-9
• TNF
• Fibrinogen
• LT-A. (Lymphotoxin alpha)

49. HERITABILITY OF AGGRESSIVE PERIODONTITIS
• Numerous studies have reported familial aggregation for aggressive periodontitis.
• Spektor MD in 1985 has shown that both forms of AP (LAP & GAP) has genetic mode of
inheritance within the families.
• Marazita et al. in 1994 had evaluated more than 100 US families, which included 527 cases and
healthy subjects with aggressive periodontitis and found the data to be more consistent with
an “Autosomal Dominant” transmission.

50. GENES ASSOCIATED WITH AP RISK:
• IL-1 cluster, IL-4,6,10,12,13,18
• TNF-a
• TGF-b
• Vit D receptor
• Estrogen receptor,
• MMP 1,2,3,9,
• HLA (human leukocyte antigen)
• CD14
• Cathepsin C, IFN-gamma.

51. Segregation Analysis:
• Most of the evidence for a genetic predisposition to aggressive periodontitis comes
from segregation analyses of families with affected individuals in two or more
generations
• Segregation analysis with human families are hampered by various methodological
factors, which often are the lack of adequate statistical power due to small number of
families, too small or incomplete families, and a high heterogeneity between families.

52. LINKAGE & ASSOCIATION ANALYSIS:
• This method determines the chromosomal location of a gene that affects the specific
observable traits in the disease.
• For a gene that influences the disease to be identified by this technique, it must have a
“Substantial effect” on the disease, and its effects must be independent of other genetic and
environmental factors.
More recently, a powerful linkage analysis technique called “Transmission disequilibrium testing” was used
with AP cases and found a significant role for polymorphisms in IL-1 genes on chromosome 2q.
( Li Y in 2004).

55. HERITABILITY OF CHRONIC PERIODONTITIS:
• Genetics has only recently emerged as a major consideration in chronic periodontitis.
i. Although bacterial plaque is essential for the initiation and progression of periodontitis, the
amount of plaque is not a good predictor of the severity of destruction.
ii. Studies of identical twins who were separated at birth and raised in different families
showed that they develop similar levels of periodontitis as adults.

56. • Michalowicz et al; in 2000 conducted population-based twin study on 117 twin pairs,
assessed the heritability of the genetic and environmental variation in chronic periodontitis
and gingivitis. It showed that the investigated MZ twins (64 pairs) were more similar than DZ
twins ( 53 pairs) for CAL, the severity and the extent of the disease.
• The heritability was estimated to be ~50%, which was unaltered for smoking, oral hygiene, age
and gender.
GENES FOR CHRONIC PERIODONTITIS
•Interleukin-1, 2, 4, 6, 10
•Fc gamma receptor
•TNF
•Vitamin D receptor

57. PERIODONTITIS IN GENETIC SYNDROMES
AND OTHER DISEASES
• Diseases that follow predictable and generally simple patterns of transmission have
been called Mendelian conditions.
• These diseases follow a classic Mendelian mode of inheritance (autosomal dominant,
autosomal recessive, or X-linked).
• Usually, the prevalence of these Mendelian conditions is rare (typically much less than
0.1%)
PAPILLON-LEFEVRE SYNDROME
EHLERS – DANLOS SYNDROME
CHEDIAK HIGASHI SYNDROME
CYCLIC NEUTROPENIA
LEUKOCYTE ADHESION DEFICIENCY

58. PAPILLON – LEFEVRE SYNDROME
• Rare autosomal recessive congenital differentiation disorder of
chromosome 11p14-q21.
• Occurs in children from consanguineous marriages.
Gene responsible: Cathepsin C, lysosomal protease
• Cathepsin C is suggested to be implicated in a wide variety of
immune and inflammatory processes
(Toomes et al. 1999).
Prevalence : 1-4 per million, equal in males and females.
(Hattab et al. 1995)

59. Clinical features:
• Hyperkeratosis of the palms and soles k/a
palmoplantar keratoderma. (either diffuse or
localized)
(Kressin et al. 1995).
• Generalized rapid destruction of the
periodontal attachment apparatus resulting in
premature loss of both primary and
permanent teeth.
• Destructions of periodontium follows almost
immediately after the eruption of last molar
tooth.
(Deas et al. 2003).

60. Histologic features:
• Gingiva demonstrates epithelial hyperplasia,
increased collagen synthesis, parakeratosis,
acanthosis, and focal aggregates of lymphocytes
and plasma cells.
• In addition, reduced osteoblastic activity and
reduced thickness of cementum have been
described
(Ghaffer et al. 1999; Hattab et al. 1995).

61. Virulence factor:
• Gram-negative anaerobic microbiota has been considered to be an important
initiator of the destructive periodontitis observed in these patients.
• Aggregatibacter actinomycetemcomitans has been reported to be the major
periodontal pathogen.
• Capnocytophaga gingivalis, black-pigmented Bacteroides, and Fusobacterium spp :
subgingival periodontal lesions in Papillon-Lefèvre syndrome patient
(Velazco et al. 1999)

62. PLS has been associated with:
• decreased neutrophil chemotaxis
• reduced random neutrophil migration
• impaired neutrophil phagocytosis
• reduced myeloperoxidase activity
• increased superoxide radial neutrophil production,
• associated with a decreased lymphocyte response to pathogens
(Lundgren et al. 1998; Velazco et al. 1999).

63. Treatment
• In the past, retinoids and antibiotics have been used with a successful dental maintenance for
one year.
• An alternative to rehabilitation with conventional dental prosthesis after total loss of the natural
teeth was the partial bone graft technique.
• It is the repositioning of bone from parietal to the maxillary bones, and placement of dental
implants in a completely edentulous maxilla when the patient has already lost all teeth.
• The maintenance of teeth is done by scaling and root planning with the use of systemic
antibiotics.

64. EHLER DANLOS SYNDROME
• Also known as
dystrophia mesodermalis or
fibrodysplasia elastica.
• Heterogenous group of inherited disorders of
connective tissue, which may affect the skin,
ligaments, joints, eyes, and vascular system
(Reichert et al. 1999).
• EDS is divided into 11 types in accordance with clinical,
genetic, and biochemical features
(Majorana and Facchetti 1992).

65. Etiology:
• Type I or type II collagen deficiency, a lysyl hydroxylase deficiency
• Deletion of N- terminal telopeptide, or
• Disorders of copper homeostasis and fibronectin defects
(Reichert et al. 1999).

66. Associated features:
• Periodontal conditions have been reported with EDS types I, VII, and VIII.
• Defective dentinogenesis, resulting in aplasia or hypoplasia of root development affecting the
mandibular incisors, and predisposition for localized periodontal disease was reported in EDS
type I.
• Ligneous periodontitis (generalized membranous gingival enlargement due to an accumulation
of fibrin deposits associated with severe alveolar bone loss)

67. • EDS type VII is an autosomal dominant/ recessive disease.
Associated features:
• Poor healing after extractions
• Prevelance of dental caries
• A radiographic evidence of bulbous enlargement of the roots
and pulp stones have been described.

68. • EDS type VIII is an autosomal dominant form.
Associated features:
• Fragile skin
• Abnormal scarring
• Early onset of periodontal disease, with
premature loss of the permanent teeth.
• Fragility of the alveolar mucosa and increased
bleeding tendencies have also been suggested

69. Treatment
• No cure for Ehlers–Danlos syndromes is known, and treatment is supportive.
Pain management:
• Nonsteroidal anti-inflammatory drugs (NSAIDs) may help if the pain is caused by inflammation.
• Opioids have shown efficiency in some EDS cases for management of both acute and chronic
pain.
• Lidocaine can be applied topically after subluxations and painful gums.
• If the pain is neuropathic in origin, tricyclic antidepressants in low doses can be used.
Surgical management:
• The instability of joints, leading to subluxations and joint pain, often requires surgical
intervention in people with EDS.
• Common surgical procedures are joint debridement, tendon replacements and arthroplasty.

70. CHEDIAK – HIGASHI SYNDROME
• It is a rare autosomal recessive disease associated
with impaired function of cytoplasmic microtubules
or microtubule assembly in PMNs
(Oh et al. 2002).
• The susceptibility to infections, although humoral and
cellular immunity are normal, leads to early death
(often before 5 years of age).

71. Clinical features:
• The disease reveals itself periodontically by
 Severe gingivitis and
 Rapid loss of attachment, leading to exfoliation of
the teeth.
• Oculocutaneous albinism: Patients are prone to
infections, especially with Staphylococcus aureus,
as well as Streptococci.
• Associated features include abnormalities in
melanocytes (albinism), nerve defects, and
bleeding disorders.

72. Treatment
• No specific treatment.
• Bone marrow transplants appear to have been successful in several patients.
• Infections are treated with antibiotics and abscesses are surgically drained when appropriate.
• Antiviral drugs such as acyclovir have been tried during the terminal phase of the disease.
• Cyclophosphamide and prednisone can be used.

73. CYCLIC NEUTROPENIA
• Rare condition, characterized by cyclical depletion of polymorphonuclear leukocyte numbers,
typically in 3-week cycles, although this can be between 2 and 5 weeks.
• Episode of neutropenia is usually short, but the patient leukocyte count never returns to normal
levels, and the differential blood-cell count for leukocytes is at least 40% less than normal levels.

74. Periodontal manifestations:
• Inflamed gingiva
• Gingival ulceration
• Periodontal attachment, and bone loss
(Kinane 1999; Rezaei et al. 2004)

75. Treatment
• Monitoring white blood cells several times a year.
• Preventive therapy includes granulocyte colony-stimulating factor (G-CSF), in the form
of filgrastim, which regulates the production of neutrophils within the bone marrow.
• Another alternative is hematopoietic stem cell transplantation (HSCT)

76. LEUKOCYTE ADHESION DEFICIENCY
• LAD is a rare but well-defined autosomal recessive disease that results in the formation of
nonfunctional intracellular adhesion molecule (ICAM receptor).
• Two LADs have been described in humans:
LAD I
LAD II
• Both diseases block a sequence of leukocyte-endothelial-cell interactions, which is generally
referred to as the multistep adhesion cascade.

77. • The disease results from mutations in the region on the CD18 gene encoded on chromosome 21q22.3,
which codes for the B2 integrin (ITGB2) subunit of the leukocyte adhesion molecule.
• The defective or absent expression of these molecules on the surface of leukocytes decreases their
ability to adhere to endothelial cells and to migrate to sites of infection.

78. Clinical features
Usually present in infancy or early childhood and consist of
• Recurrent, indolent bacterial infections of the skin, mouth,
and the respiratory tract.
• Delayed separation of the umbilical cord.
• Skin infections may progress to large chronic ulcers that
may become polymicrobial in character.
• These individuals are susceptible to fungal infections
• In addition, lack of swelling, redness, heat, or pus is noted
in the area of the infection

79. Periodontal features:
• Severe gingivitis with an early loss of primary
teeth, followed by the early loss of secondary
teeth, is seen.
• Individuals with LAD defect in innate host
defense display a severe form of periodontitis
that does not require specific periodontal
pathogens because of entrapment of
neutrophils within the blood vessel.

80. Treatment
• Although patients can receive intensive antibiotic therapy and even granulocyte
transfusions from healthy donors, the only current curative therapy is the hematopoietic stem
cell transplant.
• However, progress has been made in gene therapy, an active area of research.
• Both foamyviral and lentiviral vectors expressing the human ITGB2 gene under the control of
different promoters have been developed and have been tested so far in preclinical LAD-I
models (such as CD18-deficient mice)

81. GENE LIBRARY
• In humans, approximately 25,000 genes exists among the 3 billion base pairs of DNA
in the genome.
• To study anyone of these genes, a researcher first isolates it from all of the other
genes in an organisms DNA.
• One isolation method has a relatively long history and involves the construction of a
DNA library.
• When a gene is identified and copied, it is said to have been “cloned”.

82. • Gene Library is a large collection of DNA fragments cloned from a given organism,
tissue, organ, or cell type.
• It may contain entire genomic sequences or complementary DNA sequences formed
from messenger RNA .
GENE
LIBRARIES
Genomic
library
cDNA
library

83. GENOMIC LIBRARY
• A genomic library is
a collection of the
total
genomic DNA from
a single organism.
• The DNA is stored
in a population of
identical vectors,
each containing a
different insert of
DNA.
cDNA LIBRARY
• A cDNA library is a
combination of
cloned cDNA
(complementary
DNA) fragments
inserted into a
collection of host
cells, which
constitute some
portion of
the transcriptome of
the organism and
are stored as a
"library".

85. USES OF GENOMIC LIBRARY:
• first step in any DNA sequencing projects.
• helps in identification of the novel pharmaceutically important genes.
• can explore the genome of an organism to learn more about genomic structure and function.
• Gene mapping.
• Useful in Recombinant DNA Technology, helps to genetically modify organisms and produce
clones of desired types.

86. GENE THERAPY
• Gene therapy is a technique for correcting defective genes responsible for disease
development.
• It involves the transfer of a therapeutic or working gene copy into specific cells of an individual
in order to repair a faulty gene copy, which is to cure or to favorably modify the clinical course
of a condition.

87. MECHANISM: A vector delivers the
therapeutic gene into a
protein target
Target cells become infected
with viral vector
Vector’s genetic material is
inserted into the target cell
Functional proteins are
created from the therapeutic
gene
Cells return to a normal state

88. GOALS OF GENE THERAPY:
i. Replacing a mutated gene that causes disease with a healthy copy of the gene.
ii. Inactivating or “knocking out” a mutated gene that is functioning improperly.
iii. Introducing a new gene into the body to help fight a disease.

89. FUNDAMENTALS OF GENE THERAPY:
There are a variety of different methods to replace or repair the genes targeted in gene therapy
• A normal gene may be inserted into a non-specific location within the genome to
replace a non-functional gene.
• An abnormal gene could be swapped for a normal gene through homologous
recombination.
• An abnormal gene could be repaired through selective reverse mutation, which returns
the gene to its normal function.
• The regulation ( the degree to which a gene is turned on/off) of a particular gene could
be altered.
• The spindle transfer is used to replace entire mitochondria that carry defective
mitochondrial DNA.

90. GENE DELIVERY:
• The preferred strategy for gene transfer depends on the required duration of protein release and
the morphology of the target site production.
• There are various methods for gene delivery:
a) VIRAL
i. Retrovirus
ii. Adenovirus
iii. Adeno - associated virus
iv. Herpes simplex virus
b) NON-VIRAL:
i. Direct introduction of therapeutic DNA into target cells.
ii. Use of a liposome (artificial lipid sphere with an aqueous core).

91. IMPLICATIONS OF GENE THERAPY IN PERIODONTICS:
• In periodontics, currently genetic principles are being applied along with tissue
engineering for periodontal rehabilitation.
• Approaches
i. Protein-based approach
ii. Cell-based approach
iii. Gene-delivery approach

92. PROTEIN-BASED APPROACH:
• Growth & differentiation factors are used for regeneration of periodontal tissues like TGF-β,
BMP-2,6,7,12, bFGF, VEGF & PDGF.
CELL- BASED APPROACH:
• Several studies using mesenchymal stem cells have demonstrated efficient reconstruction of
bone defect that are too large to heal spontaneously.
GENE DELIVERY APPROACH:
• To overcome the short half-lives of growth factor peptides in vivo, gene therapy that uses a
vector that encodes the growth factor is utilized to stimulate tissue regeneration.

93. IMPLICATIONS OF GENE THERAPY IN PERIODONTICS
1. Gene Therapeutics-Periodontal Vaccination
2. Genetic Approach to Biofilm Antibiotic Resistance
3. An In vivo Gene Transfer by Electroporation for Alveolar Remodeling
4. Antimicrobial Gene Therapy to Control Disease Progression

94. Gene therapeutics-periodontal vaccination:
• A salivary gland of a mouse when immunized using plasmid DNA encoding the Porphyromonas
gingivalis fimbrial gene produces fimbrial protein locally in the salivary gland tissue resulting in
the subsequent production of specific salivary immunoglobulins, IgA and IgG and serum IgG
antibodies.
• This secreted IgA could neutralize P. gingivalis and limit its ability to participate in plaque
formation.

95. Genetic Approach to Biofilm Antibiotic Resistance
• Researchers have found bacteria growing in biofilms become up to 1,000 fold more resistant to
antibiotics as compared to a planktonic counterpart making them hard to control.
• Recently Mah et al. (2012), identified gene encoding for glycosyl transferase required for the
synthesis of periplasmic glucans in wild form of Pseudomonas aeuroginosa RA14 strain.
• This remarkably protected them from the effects of antibiotics biocides, and disinfectant.

96. An In vivo Gene Transfer by Electroporation for Alveolar Remodeling:
• Using an in vivo transfer of LacZ gene (gene encoding for various bone remodeling
molecules) into the periodontium and using plasmid DNA as a vector along with
electroporation for driving the gene into cell, has shown predictable alveolar bone
remodeling.
Step A- Cells obtained from outpatient skin biopsy
Step B- Gene of therapeutic interest is introduced into
cells by electroporation
Step C- Genetically engineered cells are propagated
and characterized
Step D- Genetically engineered cells are returned
back to clinician

97. Antimicrobial gene therapy to control disease progression:
• One way to enhance host defense mechanism against infection is by transfecting host cells
with an antimicrobial peptide/protein- encoding gene
• Researchers have shown when host cells were infected in vivo with β defensin-2 (HBD-2) gene
via retroviral vector; as a result, there was a potent antimicrobial activity which enhanced
host antimicrobial defenses.

98. LIMITATIONS OF GENE THERAPY:
i. Difficulty in delivering of gene
ii. Short-lived nature of the gene therapy
iii. Activation of immune response
iv. Chance of inducing a tumor (Insertion mutagenesis)
vi. Difficulty to treat multi gene disorders
vii. Expensive.

99. CONCLUSION
Genetics is a major determinant of the severity of
chronic periodontitis in adults.
It must be emphasized that this type of genetic
influence is different from the “single gene” defects
or chromosome abnormalities in which a genetic factor
causes a disease.
It is likely that a few genetic variations with a high
prevalence in the population will be found to
influence chronic periodontitis.
Currently, the presence if IL-1 gene variations
appear to identify individuals who are at increased
risk for more severe disease and for less predictable
response to therapy.

100. REFERENCES
• Carranza’s clinical periodontology-11th ed.
• Jan Lindhe, Niklaus P. Lang -6 th; Clinical periodontology and Implant Dentistry.
• Thomas G. Wilson, Kenneth S. Kornman, Fundamentals of Periodontics- 2nd ed.
• Thomas C. Hart & Kenneth S. Kornman, Genetic factors in the pathogenesis of periodontitis;
Perio2000, vol 14, 1997, 202-215.
• Kinane FD et al, The genetic basis of periodontitis; Perio2000 ,Vol 39, 2005, 91-117.
• Vijayalakshmi R et al, Genetic polymorphisms in periodontal diseases: An overview Indian JDent
Res, 21(4), 2010.
• Chatterjee A, Singh N, Saluja M. Gene therapy in periodontics. J Indian Soc Periodontol
2013;17:156-61.
• Siddique N et al, Gene Therapy: A Paradigm Shift in Dentistry; Genes 2016, 7, 98.
• Silva MK et al, Genetic Factors and the Risk of Periodontitis Development: Findings from a
Systematic Review; Int J Dent.2017; 2017: 1914073.

101. THANK YOU