This chapter discusses the diagnosis and epidemiology of panic disorder (PD). Genetic studies, while instrumental, cannot alone address the etiological complexities of most psychiatric disorders. The chapter turns to two integrative approaches that combine genetics with other clinical or biological methods to target the underlying mechanisms. First, it discusses exploiting the relationship between psychiatric and non-psychiatric medical manifestations (the expanded spectrum approach). This approach is particularly relevant to PD, where the panic attacks are accompanied by a range of physiological responses that may be central to the etiology. Second, the chapter describes neurobiological phenotypes, and in particular, on using measures of brain structure and function to identify genetic variation, and studies the mechanisms via which genes can impact behavior. The chapter concludes with an overview of imaging genetic studies of PD, and particularly, of how data from imaging studies can be used to enhance the tractability of genetic targets.

This chapter reviews evidence supporting the hypothesis that genetic inheritance plays a substantial role in dependence on cocaine and (to a less well-studied degree) other illicit psychostimulants. The role of genes in cocaine dependence, however, may largely reflect a more general liability to develop dependence on a variety of substances. Studies of molecular genetic mechanisms in cocaine dependence remain in an early stage of development. A genome-wide association study (GWAS) of methamphetamine dependence, while yielding some interesting leads, requires replication in light of its small size, and reliance on pooled genotyping. While several intriguing candidate-gene associations between specific loci and cocaine dependence have been reported, to date there has yet to be a definitively replicated result reported. Clearly, more work is required in the human genetics of stimulant dependence, to identify and characterize how specific genes influence risk for this set of disorders.

In the last decade, there has been an increasing appreciation of the role of genetic influences on many child behavioural traits and disorders. Most psychiatric disorders are considered genetically complex and conduct disorder is no exception. The astonishing rapidity of advances in molecular genetics is now being applied to child psychiatry. Early molecular genetic studies of adult psychiatric disorders used strategies designed to detect single genes whose individual effects accounted for a very substantial proportion of the phenotypic variance. Molecular genetic studies have relevance to conduct disorder both through the study of phenotypes in which aggression is a prominent feature and also through other psychiatric disorders such as hyperactivity and alcohol and drug abuse, which are frequently comorbid with conduct disorder or anti-social personality. A long-term goal of genetic research must be to aid in prevention and treatment of conduct disorder.