Risk Factors in Periodontal Disease - Genetics

Question 1

What percentage of the variance in the periodontitis trait in humans is attributable to heritable factors?

Answer 1

1/3 = 33%

Question 2

What are the 2 pathways for periodontitis disease heritability?

Answer 2

1. Single gene defects

Autosomal dominant (e.g. Huntington disease)
Autosomal recessive (e.g. sickle cells anaemia)
X-linked

2. Polygenic/multifactorial diseases (inherited susceptibility)

Question 3

What are the majority of genetic-periodontits cases?

Answer 3

1. Most have a polygene susceptibility profile.
2. Meaning a combination of predisposing genes with environmental factors and bacteria.
3. Only a few cases occur as single-gene defects.

Question 4

What are single gene defect genetic-periodontitis associated with?

Answer 4

Other medical conditions such as:

1. Neutrophil diseases such as congenital neutropoenia

Question 5

What are polygenic profilegenetic-periodontitis associated with?

Answer 5

Gene variants in:

1. Vitamin D receptor (VDR)
2. Fc-deltaRIIA gene
3. Interlukin 10 gene

Question 6

What are periodontal infectogenomics?

Answer 6

Study of the effect of host genetic variants on the composition of the subgingival microbiota.

Question 7

What is genetic dysbiosis?

Answer 7

Shift in composition of biofilm due to host genetic variants.

Question 8

How do epigenetic modifications occur and what is their effect on periodontitis in comparison to single gene variants?

Answer 8

1. Chemical changes in DNA consitute the ‘epigenome’ and are responsive to environmental and endogenous signals.
2. Epigenetic modifications (the spectrum of working and non working genes) can arise in the first stages of ontogenesis and persist from one cell division to the next during several cell generations.
3. They may have an effect on periodontitis beyond the effect of single gene variants.

Question 9

What are epigenomic effects connected to in terms of DNA structure?

Answer 9

1. Covalent attachment of different chemical groups to DNA
2. Chromatin
3. Histones

Question 10

what is POC testing and why may it be used on periodontal patients?

Answer 10

Point of care testing (chair-side) based on saliva, GCF, cell and bacteria sampling.

May be used on periodontal patients to identify:

1. Highly susceptible patients
2. A periodontal initial lesion when it is not yet clinically detectable.
3. To intercept the so called ‘active phase’ of periodontitis.

Question 11

What gene markers are indicators of low risk oral inflammation?

Answer 11

1. Beta defensin 1 (DEFB1)
2. CD14 (CD14)
3. Toll-like receptor 4 (TLR4)

Question 12

What gene markers are indicators of intermediate risk oral inflammation?

Answer 12

1. Tumour necrosis factor alpha (TNF-alpha)
2. Interlukin 1 (IL1)
3. Interlukin (IL6)
4. Interlukin 17A (IL17A)
5. Matrix Metallopeptidase 3 (MMP3)

Question 13

What is periodontitis’ genetic background described as?

Answer 13

Heterogeneous

Question 14

What can be done to control the risk of genetic-periodontitis?

Answer 14

1. Not much we can do to prevent.
2. But being aware of higher susceptibility can help with long-term management.