09/18 - Susceptibility to Periodontal Diseases Flashcards
What is the definition of susceptibility?
the state of being easily affected, influenced, or harmed by something
True or false: Different forms of periodontitis may have different etiologic factors.
true
The magnitude and quality of the periodontal tissue changes are determined not only by the bacteria, but also by ___ and ___.
- the patient’s genetics
- environmental modifiers
What 3 factors determine the clinical disease severity of periodontitis?
- genetic modifiers
- specific bacteria
- environmental modifiers
True or false: Periodontopathic bacterial flora is necessary but not sufficient for disease.
true
What is the odds ratio that smoking will increase periodontitis? For diabetes?
- smoking: 2.5-3.7
- diabetes 2.8-3.4
What is the definition of Mendalian inheritance? What are the modes of inheritance? What is it also known as?
- the manner by which genes and traits are passed from parents to their children
- autosomal dominant, autosomal recessive, x-linked dominant, and x-linked recessive
- AKA classical or simple genetics or single gene disorders
What is the definition of chromosome disorder?
an abnormal condition due to something unusual in an individual’s chromosomes
What is the definition of complex gene disorders? What are some examples?
- conditions caused by the effects of multiple genes in combination with lifestyle and environmental factors
- ex. cardiovascular disease, diabetes mellitus, and destructive periodontal disease
What is the definition of polymorphism?
exists when two or more different phenotypes exist within different individuals within the same population; in the context of genetics, it refers to a region of the genome that varies between individual members of the population in such proportions that the rarest of them cannot be maintained just by recurrent mutation
What is the definition of SNP? How often are they seen?
- single nucleotide polymorphisms are the most common type of genetic variation; each represents a difference in a single nucleotide
- occur normally throughout a person’s DNA, once in every 300 nucleotides so there are roughly 10 million SNPs in the human genome
What 3 things do complex genetic disorders involve?
- multifactorial (polygenic) interactions
- gene-gene interactions
- gene-environment interactions
What are the 5 characteristics of complex gene traits?
- common in population
- no clear familial transmission
- adult age onset
- environmental factors etiologic too
- combination of multiple small genetic and environmental factors
Which type (simple or complex) genetic disease is described?
- single etiologic gene
- gene has major effect
- simple pattern of transmission
simple genetic disease
Which type (simple or complex) genetic disease is described? - phenotype usually less modified by environmental interactions
simple genetic disease
Which type (simple or complex) genetic disease is described? - chronic onset
complex genetic disease
Which type (simple or complex) genetic disease is described?
- many genes may contribute to etiology
- contribution of each gene is individually small and cannot cause disease alone
- complex pattern of transmission
complex genetic disease
Which type (simple or complex) genetic disease is described? - usually acute onset
simple genetic disease
Which type (simple or complex) genetic disease is described? - phenotype continuum; environmental factors can be very important to phenotype
complex genetic disease
What 3 types of defects may make a person more susceptible to periodontitis?
- structural defects (mucosa, collagen)
- immune response defects (cytokines)
- white blood cell defects (neutrophils, macrophages)
What are the 4 reasons why it is not realistic to expect a single gene polymorphism (SNP) will be diagnostic for a complex genetic disease?
- no single gene contributes enough to cause disease alone (in contrast to Mendelian disease)
- environmental factors are important and required to cause disease
- need to study many (thousands) of people in standardized way to identify an association between a SNP and disease state
- human populations are mixed in terms of gene polymorphisms and environmental exposures, making studies difficult to control
