Twelve years have elapsed since the first edition of Metabolic Diseases: Foundations of Clinical Management, Genetics and Pathology was published. In the 21st century, traditional morphologic descriptions of pathologic processes have at least in part, been replaced by in-depth understanding of molecular genetics and by the use of newer techniques for Metabolic Diseases that affect the development and function of the embryo, fetus and infant. This second edition of Metabolic Diseases has been expanded to include the advances in molecular and genetic sciences. We have invited the knowledge and expertise of 31 authors: Karl Anderson, Heather Bartlett, Michael Bennett, Nancy Braverman, Randy Chandler, Margaret Chen, Maria Daniela D'Agostino, Philip Farrell, Carlos Ferreira, Can Ficicioglu, Theodore Friedman, Larissa Furtado, William Gahl, Eric Gou, Cary Harding, Richard Kelley, Uta Lichter-Konicki, Jennifer Mayer, William Nyhan, John Opitz, Dinesh Rakheja, J. Carter Ralphe, Allen Root, Pierre Russo, Bruce Schnapf, Lee Shulman, Jürgen Spranger, Mariana Usatli, Charles Venditti, Charles Weinstein, and Kondi Wong with the aim to present a comprehensive and detailed account which brings together and covers a wide spectrum of metabolic diseases. It is our hope that these volumes will open new avenues and vistas for our readers and that they will share with us the interest, excitement and passion of all these challenging disorders.

The approach to the diagnosis and access to specialized laboratories for specific testing has been included. Numerous tables, diagrams, and line drawings have been enhanced. Three appendices have been rewritten and updated, but the information from the others such as the one providing treatment recommendations has been incorporated into the relevant chapters. A current genome map has not been included because the available versions are being constantly improved, with updated gene sequences and locations of intronic elements, revised lists of benign SNPs, additional reference genomes, databases of variant frequencies that are ethnicity-specific, and associations of specific genes with specific human diseases such as the cancer cell genome map initiative. More information on genome maps and references is provided in chapter 1, but readers should follow specific literature closely as this field has become more specialized.

Finally, words fall short in expressing to all the contributors our gratitude on this book and their willingness to revise and update their chapters. Over the past 40 years, Dr. Gilbert-Barness has had the extraordinary good fortune of collaborating with Dr. John Opitz, Distinguished Master of Medical Genetics, a scholar, a gentleman, and a treasured friend. This rewarding experience has been beyond all measure the highlight and most important influence in her professional career. The editors are all grateful Yale Altman for his helpful suggestions and jokes, Maureen Twaig for her support and managing this publication, and especially Kathleen Lonkey; without her efforts, enthusiasm, and expertise, this book would not have been possible. The coordinating editor, Dr. Philip Farrell, in his efforts to ensure a completely updated book has greatly appreciated the encouragement and efforts of the contributing authors and is especially grateful to Dr. William Gahl for advice on the appendices and other components of this edition. Dr. Farrell also expresses his deep gratitude to his wife of 50 years, Alice, and their family for patience and support during the intensive 2 year period needed to complete this project on behalf of our good friends, Enid and Lew.

The editors

Enid Gilbert-Barness, Lewis A. Barness, and Philip M. Farrell