K.K. Jain, Textbook of Personalized Medicine, DOI 10.1007/978-1-4939-2553-7_13, 461
© Springer Science+Business Media New York 2015
Chapter 13
Personalized Management of Psychiatric
Disorders
Introduction
Most psychiatric disorders, including schizophrenia, major depression, and bipolar
disorder, are considered polygenic. The fi eld of psychiatric genetics has developed
considerably in recent years as genome-wide studies have revealed interesting vari-
ants. Using SNPs or a small set of SNPs is considered to be an excellent tool to
discover genes for psychiatric disorders and potentially an excellent tool for psy-
chopharmacogenetics as well. There are, however, a few obstacles for their use: (1)
high-throughput, low-cost genotyping assay systems; (2) defi nitions of good dis-
ease phenotype; (3) a good collaboration effort among geneticists, epidemiologists,
and physicians; (4) a good candidate gene(s). Selecting good candidate genes is
particularly diffi cult at the current time, because pathophysiology is unknown in
most psychiatric disorders. However, if one can identify a good candidate gene(s),
association study using SNPs has more statistical power than linkage analysis. It has
been demonstrated that when dealing with a gene that contributes 1–5 % additive
effect to phenotype, a huge number of subjects (more than 3,000) is required for
linkage study but not for association study. The complexity of the regulation of gene
transcription and its interactions with environmental factors implies that straightfor-
ward translation of individual genetic information into personalized treatment of
psychiatric disorders is unlikely, but integration of data from genomics, proteomics,
metabolomics, and biomarkers may enable the development of personalized use of
antidepressants (Holsboer 2008 ).
Before 2008 only a handful of gene variants involved in psychiatric illnesses had
been identifi ed, but by 2014 ~200 have been found in the human genome, including
common and rare variations and CNVs. Many of these variants (>100) appear to
play roles in schizophrenia and autism. Considerable more work needs to done as
there may be as many as 8000 gene variations or CNVs involved in schizophrenia.