636H
Fig. 11.14 Aggressive periodontitis with generalized bone loss in a 16-year-old male.
11.11.3 Genetic factors and aggressive diseases
The increased prevalence of aggressive periodontitis in certain ethnic groups and
within families strongly suggests that susceptibility to these diseases may be
influenced by a number of genetic determinants. Furthermore, genetic factors are
implicated in the pathogenesis of the diseases as many affected patients have
functionally defective neutrophils.
The mode of transmission has not been determined unequivocally. The apparent
increased incidence in females suggests an X-linked dominant mode of inheritance
with reduced penetrance. The association with females, however, may reflect
epidemiological bias as females are more likely to seek dental attention. Large family
studies of subjects with aggressive periodontitis suggest an autosomal-recessive
pattern of inheritance.
The role of hereditary components in periodontal diseases has been supported by the
link with specific tissue markers. The major histocompatibility complex (MHC)
determines the susceptibility of subjects to certain diseases. Class I and II genes in the
MHC encode for specific human leucocyte antigens (HLA I and II), which account
for individual variation in immunoresponsiveness. There are clear associations
between HLA serotypes and diabetes mellitus and rheumatoid arthritis. A strong link
between an HLA serotype and aggressive diseases has still to be determined, although
a mild association between the HLA-A9 antigen and aggressive periodontitis has been
found.
Key Points
Genetic components of periodontitis:
- family associations;
- ethnic associations;
- major histocompatibility complex link;