The field of behavioural phenotypes involves the study of the cognitive and behavioural characteristics associated with genetic syndromes, leading to a fuller understanding of people with syndromes, and permits advances in knowledge regarding both atypical and typical human development. However, behavioural phenotypes offer a number of practical challenges. Behavioural phenotypes can be difficult to measure or even to define. Efforts to study gene–behaviour correlations require researchers to synthesise techniques and data from diverse fields, ranging from statistics to clinical diagnostics. In the course of behavioural phenotype studies researchers must also contend with pervasive biases emerging from ascertainment methods, choice of statistical cohorts or control groups, and so on. In addition to these difficulties, researchers also contend with bioethical difficulties arising from tasks such as studying cognitively impaired subjects.

Key Concepts:

• Behavioural phenotypes are essential to the study of many genetic syndromes.
  
• There is often a range of behavioural phenotypes associated with a genetic syndrome.
  
• Behavioural phenotype studies have made important contributions to developmental biology.
  
• Research into behavioural phenotypes involves a range of methodological challenges, especially the need for interdisciplinary collaboration.
  
• Research into behavioural phenotypes introduces a wide variety of ethical challenges, as gene–behaviour associations can have social repercussions.