3 Schizophrenia
3.1 Personalized Medicine in Psychiatry
Relatively few examples of personalized medicine exist in psychiatry. The prob-
lems in the implementation of personalized approaches in the prediction, diagnosis,
and treatment of psychiatric diseases are very similar to those regarding the stroke.
Namely, the majority of the genetic susceptibility associations found for the mental
illness are rare genetic variants, which account for relatively small percentages of
heritability, with far greater percentages attributed to still “missing heritability.”^41
Not only genetics but also epigenetics and environmental exposures, which are still
poorly characterized, contribute substantially to the development of psychiatric
diseases and disorders. Thus, personalized approaches in psychiatry and genetic
profiling of mental illness are likely to be some way in the future too.
Schizophrenia is a severe and complex brain disorder, with high incidence
(around 0.2/1000 per year but varies significantly within populations), that is a
result of complex interaction between genetic, environmental, and social risk
factors.^42 Despite great efforts, the basic understanding of the etiopathogenesis of
schizophrenia, in which multiple and insufficiently known molecular pathways are
likely to be involved, is still incomplete. Therefore, the tools for treatment or
prevention of this disease do not exist and are urgently needed. Recent data coming
from genetic studies and system biology approaches have indicated that cellular
bases of schizophrenia do not depend only on neuronal cells, but depend also highly
on glial cells, such as oligodendrocytes, important for myelination, and on their
interactions with neurons.^43 There remains the fact that more studies are needed to
reveal and understand molecular and cellular bases of schizophrenia before the
personalized, mechanism-based therapies could be developed.
3.2 Genetic Predisposition to Schizophrenia
Schizophrenia is considered to be highly heritable, with estimated heritability of
50–80 %.^44 Numerous candidate gene studies and GWAS have shown that schizo-
phrenia is genetically very complex, with large polygenic component explaining a
substantial amount of susceptibility.^45 The high genetic susceptibility for
(^41) Ozomaro et al. ( 2013 ).
(^42) Akdeniz et al. ( 2014 ).
(^43) Roussos and Haroutunian ( 2014 ).
(^44) Ozomaro et al. ( 2013 ).
(^45) Ozomaro et al. ( 2013 ).
248 M.M. Pejatovic ́and S. Anzic ́