Oral Health and Genetics

1. Oral health and
Genetics Dr Sharanya Sreekumar
Post graduate student
Department of Public Health
Dentistry

2. Contents
Introduction
Laws of inheritance by Mendel
Genetics and dental caries
Genetics and periodontitis
Genetics and oral cancer
Classification of genetic disorders

3. Genetic disorders of oro-facial region
• Disorders of jaw bones
• Disorders of oral mucosa
• Disorders of affecting enamel
• Disorders affecting dentine
• Miscellaneous disorders
Genetic counseling
Conclusion
References

4. Introduction
The word genetics is derived from ancient Greek “genesis” meaning the origin
Imre Festetics was first person to term word genetics before Mendel.

5. Terminologies
Genotype- is the total genetic constitution of an individual
Phenotype- refer to a specified character
Chromosome: are rod-like condensations of chromatin.
They become visible in the nucleus only during cell division
Genes: are fundamental units of inheritance

6. Genetics
Modern genetics start with Gregor Johann Mendel.
 His works on monohybrid and dihybrid cross level on garden peas mentioned 3
laws of inheritance
Law of dominance
Law of segregation
Law of independent assortment

7. Genetics in oral health
Everything from the alignment of your teeth to their strength can be linked to
genetics.
The reasons for this disparity are numerous, but one of the key factors is a person’s
genetic makeup.

8. Genetics and dental caries
Children manifest the mother’s immune system for the first months of life
This acquired immune system is not particularly effective against strains of
S mutans in the mother
Inherited disorders increases chance of caries.

9. Risk assessment

11. “genetic factors play an appreciable part in determining individual resistance against
dental caries". ( Book and Grahen, 1953)
Twin studies Finn and Caldwell in 1963, found that smooth surface lesion under
genetic strict control.

12. Genetics and periodontitis
In periodontitis, the host- activated inflammatory and immunological cascades,
which result in the destruction of connective tissue and bone are under genetic
control.

13. Studies
In a large, five-generation family, an autosomal-dominant form of localized juvenile
periodontitis was ascertained to be linked to Gc (group-specific component, a
vitamin-D-binding protein locus) on the long arm of chromosome 4 (4q) (Boughman
et al, 1986)

14. Syndromes associated with periodontitis

15. Genetics and oral cancer
Oral carcinogenesis is a multifactorial process involving numerous genetic
processes that can alter the function of
oncogenes,
tumor suppressor genes, and other related molecules.

16. These changes causes loss of tumor suppressor activity and give rise to a phenotype
capable of
increasing cellular proliferation,
weakening cell cohesion and
causing local infiltration and metastasis.

19. More than 90% of oral cancer is oral squamous cell carcinogenesis which caused
due to genetic alterations
Other molecules associated are
COX-2
EpCAM
MMP-2,6

20. Genetic disorders
There are three types of genetic disorders:
Single-gene disorders
 Chromosomal disorders disorder
Complex disorders
Genetic test on blood and other tissue can identify genetic disorders
Amniocentesis genetic test.

21. Genetic disorders of oro facial regions
Most of the disorders affecting orofacial region are autosomal dominant trait
Disorder mainly affects jaws, dental tissues and oral mucus membrane

22. Disorders of Jaw bones
Cherubism :
It is a autosomal dominant disorder
Caused due to mutation SH3BP2 gene.( 80% cases)
 causes inflammation in the jaw bones and triggers the production of osteoclasts

23. Cleidocranial dysplasia
It a autosomal dominant disorder affecting development of bones and teeth.
Mutation of RUNX2 gene
abnormally short protein or gene is missing
Interferes with normal protein growth and development

24. Treacher Collins syndrome( mandibulo facial dysostosis)
Autosomal dominant trait
mutation of gene EFTUD2
Spliceosomes helps process of messengerRNA
impairs RNA processing

25. Nevoid basal cell carcinoma syndrome
It is autosomal dominant trait
Mutation of PTCH 1 gene occurs
Prevent production of patched-1
Cannot effectively suppress cell
growth and division
Cell grow uncontrollably to form
tumour

26. Osteogenesis imperfecta
It is autosomal dominant trait and sometimes have a recessive trait
 8 types have been identified.
Mutations in the COL1A1, COL1A2,
CRTAP, and P3H1 genes
Reduces amount of type 1 collagen
Causes brittle bones, defective CT

27. Apert syndrome
Autosomal dominant trait
Mutation in FGFR 2 gene
Alters FGFR287100 protein
Leads to prolonged signaling
Promote fusion in skull, hand and feet

28. Disorders of oral mucosa
Multiple endocrine neoplasia syndrome
Neurofibromatosis
Peutz-Jeghers syndrome

29. Multiple endocrine neoplasia syndrome
Tumors produced in endocrine glands.
Mutations in the MEN1 type 1 MEN Menin protein
RET gene type 2 MEN over activate protein signaling
CDKN1B genes type 4 MEN ses amount of functional p27

30. Neurofibromatosis
NF type 1 autosomal dominant
Mutations in the NF1 gene
nonfunctional version of neurofibromin
cannot regulate cell growth and division.
neurofibromas forms along nerves
.

31. Peutz-Jeghers syndrome
Inherited in autosomal dominant pattern
Mutation of STK11 gene
alters the structure or function of the STK11 protein
disrupting its ability to restrain cell division.
formation of noncancerous polyps and cancerous tumors

32. Disorders affecting dental tissues
Amelogenesis Imperfecta
Oculo-dentodigital Dysplasia
Epidermolysis bullosa
Focal dermal hypoplasia
Dentinogenesis imperfecta

33. Amelogenesis Imperfecta
14 forms of amelogenesis imperfecta.
Mutations in the AMELX, ENAM, MMP20, and FAM83H genes
tooth enamel is abnormally thin or soft
 malfunction of the proteins in the enamel: ameloblastin, enamelin, tuftelin and
amelogenin.

34. Hypoplastic type
Very less or no enamel
Hypomaturation type
Snow capped teeth
Hypocalcification
Soft and easily removable
Hypoplasic hypomaturation with taurodontism

35. Oculo-dento digital Dysplasia
Inherited autosomal dominant pattern

36. Epidermolysis bullosa
Usually autosomal dominant pattern
4 major types
mutations in either the KRT5 or KRT14 gene.
Prevent the keratin proteins from assembling into strong networks
causing cells in the epidermis to become fragile and easily damaged.
the skin is less resistant to friction and minor trauma and blisters easily.

37. Focal dermal hypoplasia
It is X-linked dominant pattern that primarily
Mutations in the PORCN gene
prevent the production PORCN protein
Wnt proteins cannot be released from the cell
Interuptes normal development

38. Dentinogenesis imperfecta
 autosomal dominant condition

39. DI type 2 and 3 caused to mutation of gene DSPP
The DSPP gene provides two proteins that are essential for normal tooth
development.
DSPP gene mutations
alter the proteins made from the gene
production of abnormally soft dentin.
DI type 1 associated with osteogenesis imperfecta

40. Miscellaneous disorders
Erythroblastosis foetalis
Progeria( Hutchnison Gliford syndrome)
Scleroderma
Cleft lip and palate

41. Erythroblastosis foetalis
Rh incompatablity caused due to mutation of RHAG gene( Rh associated
glycoprotein )
It leads to chronic hemolytic anaemia due to defect in RBC formed.

42. Progeria( Hutchnison Gliford syndrome)
rapid appearance of aging beginning in childhood
Mutations in the LMNA gene
production of an abnormal version of the lamin A protein.
nuclear envelope unstable and progressively damages the nucleus
making cells more likely to die prematurely

43. Scleroderma
It is autoimmune disorder
IRF5 and STAT4, are also associated with an
increased risk of developing systemic scleroderma
 a combination of genetic and environmental factors seems to play a role in
developing systemic scleroderma

44. Van der woude syndrome
Autosomal dominant condition
 A shortage of the IRF6 protein affects the development and maturation of tissues in
the face.

45. Genetic counselling
is a communication process in which trained professionals help individuals and
families deal with issues associated with the risk of or occurrence of a genetic
disorder.
Types
Prospective and Retrospective genetic counselling

47. Conclusion
The traditional epidemiologic approach has proved useful for generating
hypotheses and unraveling disease etiologies. But now it is possible to go beyond
these methods and look inside the genetics of the disease process which would be
able to change the definition of the risk factors or clarify their location in the
casual model. The control of genetic diseases should be based on an integrated
and comprehensive strategy combining best possible treatment and prevention
through community education, population screening, genetic counseling, and the
availability of early diagnosis

48. References
Shafer'S Textbook Of Oral Pathology (6th Edition) (2009) edited by R. Rajendran,
B. Sivapathasundharam
Purkait SK Essentials of Oral Pathology 3rd edition 2011
Rai R, Kumar PG Genetics and oral health. Dentistry and Medical Research Jan-Jun
2016; 4(1): 9-17
Werneck RI, MT Mira M, PC Trevilatt PC . A critical review: an overview of genetic
influence on dental caries. Oral Diseases (2010) 16, 613–623

49. 1000 Genomes Project Consortium. A global reference for human genetic variation.
Nature. 2015 Oct 1;526(7571):68-74.
Hamosh A, Scott AF, Amberger JS, Bocchini CA, McKusick VA. Online Mendelian
Inheritance in Man (OMIM), a knowledgebase of human genes and genetic disorders.
Nucleic acids research. 2005 Jan 1;33(suppl_1):D514-7.
Govindaraju P. Chandra P. Implications of genomics in oral health. Journal of
Advanced Clinical & Research Insights (2015), 2, 147–150
Tyagi R, Sharma A, Khatri A. Genetic Basis of Dental Disorders: A Review. J Oral
Health Comm Dent 2008;2(3):55-61