Genetic susceptibility to Periodontitis Flashcards
What are the major etiological factors for periodontitis?
Periodontium
Environmental risk factors
Host risk factors
What is the role of microorganisms in periodontitis?
Periodontopathic bacterial flora is necessary but not sufficient for disease
Are all individuals equally susceptible to periodontitis?
No
Amelogenesis imperfecta
Enamel doesn’t form
Teeth are exremely sensitive, and essentially just little stubs
Hereditary gingival fibromatosis
Gingiva overgrows everywhere
Papillon Lefevre syndrome
Hyperkeratinization
Early age onset (3-4)
Kids are normally edentulous by 5 or 6
Dentinogenesis imperfecta
No dentin is formed
There is no DEJ, can can lead to rampant caries
What is the etiological basis for most human diseases?
Gene-gene and/or
Gene-environment interactions
Mendelian genetics
If you have the gene, you have the trait
If you don’t have the gene, you don’t have the trait
Polygenic traits
Requires a bunch of different genes to develop one phenotype
Height is an example of a polygenic trait
How are polygenic traits distributed in the population?
On a bell curve
Most people are average (in the middle), but there are a few people are on the extremes
What are the different classifications of genetic disorders?
1) Single gene disorders
2) Chromosome disorders
3) Complex genetic disorders (most of the diseases we cover, including periodontitis, fall under this category
Single gene disorders
Transmitted as “simple” genetic traits
Pretty rare
Can be autosomal recessive (Papillon Lefevre Syndrome) or autosomal dominant (Hereditary gingival fibromatosis)
Chromosome disorders
Abnormal, missing, or extra chromosomes - the most common are Trisomies (missing)
An example is downs syndrome
Periodontitis can be a manifestation of chromosome disorders
Complex genetic diseases
Many genes contribute to etiology
Contribution of each gene is individually small (
What is the evidence for a genetic component of periodontitis susceptibility?
1) Association of periodontitis with Mendelian diseases
2) Twin studies of chronic periodontitis
3) Aggressive periodontitis formal genetic studies
4) Animal models
Leukocyte Adhesion Deficiency is an example of what?
Periodontal diseases with Mendelian genetics
Monozygotic twins
Have identical genes
Diazygotic twins
Share half of their genes
Disease caused wholly or partially by genetic factors will have a higher concordance rate in what type of twins?
Monozygotic
If MZ twins are not fully concordant, what does that tell us about a disease?
Environmental factors must be etiologic
What did the twin studies about chronic periodontitis tell us?
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
What can formal genetic studies tell us?
They evaluate the pattern of disease segregating in families
Can determine if disease occurs in families consistent with the genetic model
What models of genetic traits can periodontitis risk get passed?
Almost all…
Autosomal, x-linked, dominant, recessive, or sporadic
Periodontal risk can be dominant in some countries, and recessive in other
