Craniofacial development has been an important field of study over many decades for a variety of reasons. The craniofacial structures are a source of amazing morphological diversity between species reflecting an equally diverse range of feeding and sensory adaptations. The head contains numerous specialized organs for the senses of smell, sight, taste, hearing and balance and the tissues of the oral cavity participate in feeding, breathing and vocalization. Very complex cellular movements and signaling occur between cells derived from different embryonic origins resulting in an integrated, functionally complex structure. The morphological innovations that occur in the craniofacial complex and the mechanisms driving such diversity have naturally attracted attention from evolutionary and developmental biologists over a long period. Morphogenesis of the craniofacial structures is also very sensitive to environmental and genetic insults and this sensitivity leaves these structures vulnerable to an array of dysmorphology that has profound impacts on human patients and their families. Human craniofacial dysmorphology has attracted equally intense investigation from clinicians and biologists alike and is a field likely to grow rapidly under the influence of new gene identification technologies.
The development of new technologies and approaches is impacting heavily on the different groups that have traditionally studied the developmental biology of and the clinical syndromes involving craniofacial tissues such as experimental and clinical geneticists, developmental biologists, dentists, pediatricians, comparative morphologists and evolutionary biologists. While each field has had a slightly different emphasis and goal, it has become quite apparent in recent years that the boundaries between these groups, in terms of techniques, problems, model systems and clinical syndromes, are being breached, and with wonderful results. The ease of applying results from one model system to another is demonstrating the importance of understanding the basic biological programs of the evolution, transcriptional networks and cell biology of craniofacial development to clinical problems. As a result, several conferences and multi-investigator projects have begun to attract researchers in a variety of fields to tackle the underlying causes of normal and abnormal craniofacial development from several different aspects. Looking at the programs of many different scientific and clinical societies in recent years reveals sessions and satellite symposia focused on various aspects of craniofacial development.
Two highly focused conferences are of particular note. One of the oldest cross-disciplinary groups is The Society of Craniofacial Genetics, which was founded in 1975 to provide an interdisciplinary forum for basic scientists and clinicians sharing an interest in the normal and abnormal developmental biology of craniofacial structures. The Society held its first symposium, titled “Developmental Aspects of Craniofacial Morphology”, prior to the March of Dimes Birth Defects Conference in 1978. Many annual symposia followed and were published as books in the March of Dimes Birth Defects Series. In 1992, The Society affiliated with the American Society of Human Genetics (ASHG) and now holds its annual symposia in conjunction with the ASHG conventions; in 2011 it will be held in Montreal. From 1981-2000, the Society published The Journal of Craniofacial Genetics and Developmental Biology, edited by Michael Melnick. In 2004, an official website (http://craniofacialgenetics.org) was established to post the abstracts presented at the meetings (1998-present). A more recent regularly occurring conference is the Craniofacial Morphogenesis & Tissue Regeneration Gordon Research Conference. The first meeting was held in 2004, and it has met every two years since. Each meeting has sessions on the developmental biology, evolution, molecular genetics, clinical genetics and human syndromes of craniofacial structures, thus bringing together basic and clinical scientists interested in normal and abnormal craniofacial development.
Another recent advance is the development of a collaborative project, supported in the USA by the NIH National Institute of Dental and Craniofacial Research, called The FaceBase Project: Functional Genomics of Craniofacial Development and Disease (www.FaceBase.org). The purpose of this consortium of projects is to provide a central repository and database for information critical to understanding craniofacial and dental development and disease to the craniofacial research community. Currently eleven projects, that range in topics from database and technology development, creation of new animal models (see article by Stephen Murray in this volume), global gene expression atlas, miRNA screens, and 3-dimensional imaging, are being supported. Detailed information about these projects can be found at www.dentistryiq.com.
These are just a few examples to demonstrate the wide-spread interest in the problems of craniofacial development. With this explosion of interest in recent years, we are excited to present this Special Issue on Craniofacial Development. We have gathered together an intriguing mixture of reviews and research articles on a variety of topics spanning fundamental cell biology, cell signaling, gene function, gene discovery, cell lineage and evolution in various craniofacial structures and in a wide range of animals including humans. As diverse as this collection of works is, it represents only a small sample of the outstanding work going on in the field today. We hope that this special issue will help to foster new directions and collaborations from veterans as well as serving as a point of focus to attract a new generation of researchers into the burgeoning field of craniofacial development.
We would like to thank G.H. Sperber of the University of Alberta for providing the text regarding The Society of Craniofacial Genetics, and all the authors for keeping on schedule.