The term ‘behavioural phenotype’ was introduced by Professor William Nyhan in his presidential address to the Society for Paediatric Research in 1972 with a vivid description of the self mutilation that characterises the condition to which his name is attached— the Lesch-Nyhan syndrome. The observation that individuals with the same genetic disorders behave in similar ways is not new and descriptions of behaviours were included in the early descriptions of his eponymous patients by Down. The study of behavioural phenotypes and their clinical relevance diagnostically and therapeutically is receiving increasing attention. This is the first textbook designed specifically to address this topic.

The opening chapter provides an excellent introduction to the concept of behavioural phenotype and its place in genetics and developmental medicine. The interface between behavioural phenotype, psychiatric disorder, and phenotype is discussed and the complex aetiology of these phenomena explored. This work draws from a broad scientific field and subsequent chapters summarise advances in human genetics, pathways from genotype to phenotype, and lessons from fragile X syndrome. There are two chapters concentrating on methodological issues and measurement of behaviour. These provide an extremely helpful overview to this complex area for those considering research.

A major part of the book is devoted to a review of the psychological and behavioural phenotypes that are associated with a number of genetically determined disorders. The genetic underpinnings, physical features, and natural history of the more than 30 syndromes are reviewed followed by descriptions of the cognitive profiles, learning difficulties, and behavioural characteristics that are associated with each. Research in this area is in its infancy and in many cases descriptions are anecdotal. It is difficult to provide up to date information in this rapidly advancing field.

In summary, this first book specifically devoted to behavioural phenotypes summarises the work of the Society for the Study of Behavioural Phenotypes over the last few years. I feel it will be of value to professionals from both mental health and paediatric backgrounds who are working in the field of learning disability. This is a developing and controversial area and I hope this book will promote the concept of behavioural phenotypes to a wide audience.