Genetic susceptibility to Periodontitis

Question 1

What are the major etiological factors for periodontitis?

Answer 1

Periodontium
Environmental risk factors
Host risk factors

Question 2

What is the role of microorganisms in periodontitis?

Answer 2

Periodontopathic bacterial flora is necessary but not sufficient for disease

Question 3

Are all individuals equally susceptible to periodontitis?

Answer 3

No

Question 4

Amelogenesis imperfecta

Answer 4

Enamel doesn’t form

Teeth are exremely sensitive, and essentially just little stubs

Question 5

Hereditary gingival fibromatosis

Answer 5

Gingiva overgrows everywhere

Question 6

Papillon Lefevre syndrome

Answer 6

Hyperkeratinization
Early age onset (3-4)
Kids are normally edentulous by 5 or 6

Question 7

Dentinogenesis imperfecta

Answer 7

No dentin is formed

There is no DEJ, can can lead to rampant caries

Question 8

What is the etiological basis for most human diseases?

Answer 8

Gene-gene and/or

Gene-environment interactions

Question 9

Mendelian genetics

Answer 9

If you have the gene, you have the trait

If you don’t have the gene, you don’t have the trait

Question 10

Polygenic traits

Answer 10

Requires a bunch of different genes to develop one phenotype

Height is an example of a polygenic trait

Question 11

How are polygenic traits distributed in the population?

Answer 11

On a bell curve

Most people are average (in the middle), but there are a few people are on the extremes

Question 12

What are the different classifications of genetic disorders?

Answer 12

1) Single gene disorders
2) Chromosome disorders
3) Complex genetic disorders (most of the diseases we cover, including periodontitis, fall under this category

Question 13

Single gene disorders

Answer 13

Transmitted as “simple” genetic traits
Pretty rare
Can be autosomal recessive (Papillon Lefevre Syndrome) or autosomal dominant (Hereditary gingival fibromatosis)

Question 14

Chromosome disorders

Answer 14

Abnormal, missing, or extra chromosomes - the most common are Trisomies (missing)
An example is downs syndrome
Periodontitis can be a manifestation of chromosome disorders

Question 15

Complex genetic diseases

Answer 15

Many genes contribute to etiology

Contribution of each gene is individually small (

Question 16

What is the evidence for a genetic component of periodontitis susceptibility?

Answer 16

1) Association of periodontitis with Mendelian diseases
2) Twin studies of chronic periodontitis
3) Aggressive periodontitis formal genetic studies
4) Animal models

Question 17

Leukocyte Adhesion Deficiency is an example of what?

Answer 17

Periodontal diseases with Mendelian genetics

Question 18

Monozygotic twins

Answer 18

Have identical genes

Question 19

Diazygotic twins

Answer 19

Share half of their genes

Question 20

Disease caused wholly or partially by genetic factors will have a higher concordance rate in what type of twins?

Answer 20

Monozygotic

Question 21

If MZ twins are not fully concordant, what does that tell us about a disease?

Answer 21

Environmental factors must be etiologic

Question 22

What did the twin studies about chronic periodontitis tell us?

Answer 22

Monozygotic twins were twice as likely to develop chronic periodontitis than dizygotic twins
This suggests that genetics make an important contribution for the risk of periodontal disease

Question 23

What can formal genetic studies tell us?

Answer 23

They evaluate the pattern of disease segregating in families

Can determine if disease occurs in families consistent with the genetic model

Question 24

What models of genetic traits can periodontitis risk get passed?

Answer 24

Almost all…
Autosomal, x-linked, dominant, recessive, or sporadic
Periodontal risk can be dominant in some countries, and recessive in other

Question 25

What did linkage analysis tell us about the chromosomal location of aggressive periodontitis?

Answer 25

There are multiple forms, and there are many locations where is can be found genetically

Question 26

What is the one etiological factor that we can control for periodontitis?

Answer 26

Environmental - if we can control this, we can control the disease

Question 27

T/F - There are many polymorphisms reported associated with periodontitis

Answer 27

True

Question 28

Why don’t we know a bunch about the genetics of periodontitis?

Answer 28

Cause and effect relationships are difficult to prove for complex genetic diseases